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Cranes, lifts, and scaffolding are three types of equipment that, in different ways, enable work to be done at heights. Cranes lift and lower loads and move them horizontally, aerial lifts are vehicle-mounted devices used to elevate personnel, and scaffolding refers to temporary structures that employees work from. Using this equipment safely and effectively requires training and knowledge about the hazards involved, such as falls and electric shock.
Cranes, lifts, and scaffolding are three types of equipment that, in different ways, enable employees to effectively perform work from heights. Cranes lift and lower loads and move them horizontally, aerial lifts are vehicle-mounted devices used to elevate personnel, and scaffolding refers to temporary support structures. Using this equipment safely and effectively requires knowledge and training in the hazards involved, such as falls and electric shocks.
A crane is designed to lift and lower a load and move it horizontally.
Overhead and gantry cranes have a horizontal bridge across which a trolley and hoist travel. Materials being moved by overhead cranes are attached to a hoisting mechanism on the trolley.
These cranes are useful in general machine shops, fabricating assemblies, printing operations, and warehousing. They can be purchased “as is” or custom-built by the manufacturer.
Scope/Who must comply
The Occupational Safety & Health Administration (OSHA) regulates overhead cranes at 29 CFR 1910.179.
The OSHA rule applies to overhead and gantry cranes, including semi-gantry, cantilever gantry, wall cranes, storage bridge cranes, and others having the same fundamental characteristics. These cranes are grouped because they all have trolleys and similar travel characteristics.
The rule covers the safe operation of overhead- and gantry-type cranes by setting down design criteria for manufacturers, as well as the safe procedures employers must follow pertaining to crane and rope inspections, equipment maintenance, load handling, and operator training.
Training
OSHA’s overhead crane standard does not provide much detail about crane operator training. The standard simply states at 1910.179(b)(8), “Only designated personnel shall be permitted to operate a crane covered by this section.” OSHA defines designated as “selected or assigned by the employer or the employer’s representative as being qualified to perform specific duties.”
OSHA clarifies in a November 8, 1999, Letter of Interpretation that the Agency would interpret “qualified” in light of operator-qualifications provisions of industry standards such as ANSI B30.2. In addition, although the 1910.178 powered industrial truck training requirements do not apply, employers may also find it useful to consult that standard when developing a training or evaluation program for “travel lift” operators.
In general, the standard requires covered employers to:
Whether the Occupational Safety & Health Administration (OSHA) requires a safety latch on a sling hook depends on the activity for which the sling is being used. While the standard for slings provides that “[s]lings shall be securely attached to their loads,” the section does not explicitly require that the hook be equipped with a safety latch.
Use of a hook with a safety latch would, of course, be one way of securely attaching a sling to its load. (Other standards, such as those for derricks, do include explicit requirements for latch-type hooks.)
In addition, OSHA often considers the provisions of industry consensus standards when evaluating whether a hazard is “recognized” and whether there is a feasible means of abating that hazard. One such provision that OSHA considers is ASME 30.2-2001, Overhead and Gantry Cranes, which does require “latch-equipped hooks” be used if practical and necessary for the lift.
Note: OSHA does not allow employees to tie off to the hook of an overhead crane. They address this issue in a still-valid letter dated April 4, 1993: “Work cannot be performed from a suspended load or hook ...”
A mobile crane is designed to lift and lower a load and move it horizontally. Mobile cranes come in all sizes so that the task of manipulating materials can be made safer and easier.
Scope/who must comply
The Occupational Safety & Health Association (OSHA) regulates mobile cranes at 29 CFR 1910.180 — Crawler locomotive and truck cranes.
The OSHA rule applies to crawler cranes, locomotive cranes, wheel-mounted cranes of both truck and self-propelled wheel type, and any variations thereof that retain the same fundamental characteristics. This includes only cranes of the above types, which are basically powered by internal combustion engines or electric motors and which utilize drums and ropes. Cranes designed for railway and automobile wreck clearances are excepted.
Training
OSHA’s mobile crane standard does not provide much detail about crane operator training. The standard simply states at 1910.180(b)(3), “Only designated personnel shall be permitted to operate a crane covered by this section.” OSHA defines designated as “selected or assigned by the employer or the employer’s representative as being qualified to perform specific duties.”
In general, the standard requires covered employers to:
Employers are responsible for ensuring that equipment is in working order and being used safely. They are required to:
When attaching the load, the user must ensure the hoist rope is not wrapped around the load. The load must be attached to the hook by means of slings or other approved devices.
Moving the load
The user should ensure the crane is level and is blocked properly where necessary.
The load must be secured and balanced in the sling or lifting device before it is lifted more than a few inches. Load (working) means the external load, in pounds, applied to the crane, including the weight of load-attaching equipment such as load blocks, shackles, and slings.
Before starting to hoist, the following conditions must be met:
During hoisting, the operator must ensure that:
Side loading of booms is limited to freely suspended loads. Cranes must not be used for dragging loads sideways.
No hoisting, lowering, swinging, or traveling shall be done while anyone is on the load or hook.
The operator must not carry loads over people.
On truck-mounted cranes, no loads shall be lifted over the front area except as approved by the crane manufacturer.
The operator shall test the brakes each time a load approaching the rated load is handled by raising it a few inches and applying the brakes.
Outriggers shall be used when the load to be handled at that particular radius exceeds the rated load without outriggers as given by the manufacturer for that crane. Outriggers are extendable or fixed metal arms, attached to the mounting base, which rest on supports at the outer ends.
Where floats are used, they shall be securely attached to the outriggers. Wood blocks used to support outriggers shall:
Neither the load nor the boom shall be lowered below the point where less than two full wraps of rope remain on their respective drums.
A designated person shall be responsible for determining and controlling safety before traveling a crane with load. Decisions such as position of load, boom location, ground support, travel route, and speed of movement are up to the designated person.
A crane with or without load shall not be traveled with the boom so high that it may bounce back over the cab.
Holding the load
Operators are not permitted to leave their position at the controls while the load is suspended.
No person should be permitted to stand or pass under a load on the hook.
If the load must remain suspended for any considerable length of time, the operator shall keep the drum from rotating in the lowering direction by activating the positive controllable means of the operator’s station.
Operations near overhead electric lines
If work is to be performed near overhead lines, the lines shall be deenergized and grounded, or other protective measures shall be provided before work is started. If the lines are to be deenergized, arrangements shall be made with the person or organization that operates or controls the electric circuits involved to deenergize and ground them.
If protective measures, such as guarding, isolating, or insulating, are provided, these precautions shall prevent employees from contacting such lines directly with any part of their body or indirectly through conductive materials, tools, or equipment.
For employees who operate or work around cranes or derricks, it’s critical that they understand and comply with the necessary work practices established by their company to keep them safe from crane accidents.
Employees should have a basic understanding of electricity and the clearance distances necessary to minimize danger when working near power lines or other electrical sources. An understanding of the hazards associated with crane assembly/disassembly, rotating superstructures, energized equipment, and falls is also key to overall safety.
Scope/Who must comply
The Occupational Safety & Health Association (OSHA) regulates this at 29 CFR 1926 Subpart CC — Cranes and derricks in construction.
OSHA’s Subpart CC applies to power-operated equipment, when used in construction, that can hoist, lower, and horizontally move a suspended load. Such equipment includes, but is not limited to:
Employers are responsible for minimizing hazards to the extent possible and providing employees with the knowledge and resources to work safely in and around mobile cranes.
Determine ground conditions
Employers must determine whether the ground is sufficient to support the anticipated weight of hoisting equipment and associated loads.
The term “ground conditions” means the ability of the ground to support the equipment (including slope, compaction, and firmness).
Assess hazards
Employers must assess hazards within the work zone that would affect the safe operation of hoisting equipment, such as those of power lines and objects or personnel that would be within the work zone or swing radius of the hoisting equipment.
Ensure equipment is safe
Employers must ensure that the equipment is in safe operating condition by performing required inspections.
Train employees
Employers must train employees in the work zone to recognize hazards associated with the use of the equipment and any related duties that they are assigned to perform.
The employer must ensure that each operator is trained, certified/licensed, and evaluated before operating any equipment covered under 29 CFR 1926 Subpart CC.
Operator qualification requirements
Being certified doesn’t necessarily make an operator qualified. The most important way to determine an operator’s qualifications is through evaluation during the certification process. The Occupational Safety & Health Association (OSHA) has determined that an employer evaluation is necessary to determine the qualifications of an operator.
Just as a driver’s license doesn’t qualify an employee to operate all types of vehicles, certification doesn’t mean that an operator can use all types of cranes. Ultimately, there are two major issues associated with certified operators who switch to new equipment or tasks without evaluation:
Operator certification requirements
Before the evaluation process begins, operators must be trained and certified in operating either a specific crane type or a crane type with a specific rated capacity. Although employers are required to provide each operator-in-training with sufficient training, certification can be acquired through:
Third-party certification is portable. If an employee acquired certification from a previous employer, that certification is acceptable. However, employers are still required to evaluate an operator with certification, whether from a third party or not.
Until employees pass evaluation, they must be considered operators-in-training and must not use equipment without supervision.
Evaluation of operator qualification
The evaluation process should be performance-oriented. For operators to learn successfully and safely, a competency evaluation is critical. The requirements for the evaluation process have important advantages:
(Note: Employers are not required to comply with the evaluation process if operators are using derricks, side-booms, and cranes with a capacity of 2,000 pounds or less.)
Many incidents occur because an operator doesn’t have the equipment-specific knowledge to safely operate a crane. For this reason, OSHA has determined that accidents can be reduced if employers evaluate the operators’ skills and knowledge, as well as their ability to recognize and avert risk necessary to operate the equipment. Employees’ capabilities with the following should be evaluated:
The evaluation can be done by a qualified operator who has already passed evaluation or by an agent. If the employer decides to use an agent, the requirements for evaluation still apply and should be enforced.
An operator who successfully passes evaluation can operate equipment without supervision unless doing so would require different skills, knowledge, or ability to reduce risk. There may be many times when operators switch to new tasks or equipment. In those cases, a new evaluation should be performed to reduce the risk of injury to the operator or employees around the crane and equipment.
Employers should document each evaluation, providing:
Keep the documentation available on the worksite for the duration of the operator’s employment.
(Note: If an operator was hired prior to December 10, 2018, employers are allowed to rely on previous documentation and evaluations rather than conducting new ones.)
If there is an indication that an operator may need retraining, then the employer must provide retraining based on the topic(s) in question. Sometimes, an operator might forget information needed to safely operate equipment, and an accident could occur.
Of course, retraining won’t always happen because of an accident. If an operator indicates a lack of clarity about something, retraining is required. Retraining is ongoing. After the initial evaluation, operator retraining should be required as needed.
Validation of operator certification
As mentioned above, operators can be certified through a crane operator testing organization. These certifications are issued only after the operator has demonstrated through written and practical tests the knowledge and skills required to operate a crane.
In some cases, employers may hire an operator whose certification was acquired through a nationally accredited organization that no longer exists. In these cases, how can an employer ensure sure their operators are adequately certified?
It’s actually an easy question to answer, and options for solving the problem are available.
If an operator’s certification may not really have been issued by a nationally accredited organization, the best way to proceed is to do some digging and find information on the organization. Just because the organization no longer exists doesn’t mean information on its credibility or history isn’t available.
All findings should be clearly documented. Having information ready for immediate evaluation can prove useful should an OSHA inspection occur.
The typical construction crane can weigh many tons. Putting this weight on the ground at a construction site can lead to all sorts of problems. The most serious could be crane tip-over caused by the ground underneath the crane giving way.
The Occupational Safety & Health Association (OSHA) has determined that failure to have adequate ground conditions is a significant crane safety problem.
The term “ground conditions” is defined as the ability of the ground to support the equipment. Three key factors are involved in ground conditions:
Adequate ground conditions are essential for safe operations because the crane’s capacity and stability depend on those conditions being present. There are two key problems regarding ground conditions:
Stability and support
The requirements for ensuring adequate ground support apply both when assembling a crane and during actual crane operation.
The three ground support requirements are:
The responsibility for determining if the ground conditions are safe falls to the job’s controlling entity (CE). The CE is defined as an employer who is a prime contractor, general contractor, construction manager, or any other legal entity that has the overall responsibility for the project’s planning, quality, and completion.
Before any equipment is brought to the jobsite, the CE must possess and examine information (such as site drawings, as-built drawings, and soil analyses) to see if there are hazards beneath the crane setup area. If there are hazards identified in those documents, or if the CE has identified other hazards, then the CE must inform the crane user and operator of the hazards.
If the CE is not familiar with the crane or with the ground conditions at a particular jobsite, then the CE is responsible for having someone who is familiar with those requirements:
If there is no CE for the project, the ground support requirements in 1–3 above must be met by the employer who has authority at the site to make or arrange for ground preparations.
Assembly and disassembly
Before beginning assembly/disassembly (A/D), the A/D director has to determine whether ground conditions are adequate to support the equipment during that activity. If the A/D director or the operator determines that ground conditions do not meet the ground support requirements, that person’s employer must have a discussion with the CE regarding the ground preparations that are needed so that, with the use of suitable supporting materials/devices (if necessary), the ground support requirements can be met.
All power lines should be considered to be energized unless the utility owner/operator confirms the line has been, and continues to be, de-energized and visibly grounded at the jobsite. In addition, power lines should be presumed to be uninsulated unless the utility owner/operator or a registered professional engineer — who is a qualified person with respect to electrical power transmission and distribution — confirms that a line is insulated.
The Occupational Safety & Health Association’s (OSHA) 29 CFR 1926 Subpart CC requires employers to use a very specific and systematic approach to deal with the hazards of power lines.
(Note: Some of these requirements do not apply to work covered by Subpart V — Power Transmission and Distribution.)
When working near all voltages, the basic procedure is:
The employer is allowed to choose from several minimum clearance distance options.
In addition to frequent and periodic inspections, employers are required to inspect and test equipment to ensure it is capable of safe and reliable operation when initially set up or placed in service and after any major repairs or design modification.
The first step is to determine if power lines pose a hazard. To do this requires the work zone to be identified in one of the following ways:
Once the work zone is identified, it must be determined if any part of the crane, load line, or load (including the rigging and lifting accessories) could get closer than the trigger distance to a power line.
The trigger distance is as follows:
This determination should be made with the assumption that the crane will be operated up to its maximum working radius in the work zone.
If the crane will not get closer than the trigger distance to the power line, then the employer is not required to take any further action.
However, the employer may encounter a situation where it is necessary to increase the size of the work zone. This may occur as a result of an unanticipated need to change the crane’s position or have it operate beyond the original work zone boundaries. If that is the case, the employer must reidentify the work zone and conduct a new trigger distance assessment.
Operations below power lines
No part of the equipment, load line, or load (including rigging and lifting accessories) is allowed below a power line unless the employer has confirmed that the utility owner/operator has de-energized and (at the jobsite) visibly grounded the power line. Exceptions are listed in paragraph 1926.1408(d)(2).
If the crane could get closer than 20 feet to a power line, one of the three following options must be chosen.
Option 1 — De-energize and ground
Confirmation is received from the utility owner/operator that the power line has been de-energized and visibly grounded at the jobsite. This option is the safest and minimizes the possibility the crane would become energized if it did contact the line. If this option is chosen, the employer does not have to implement any of the other encroachment- or electrocution-prevention measures.
However, there are drawbacks to this. One is the time lag due to the amount of time needed to arrange for the utility owner to de-energize and ground the lines. Another is that when the construction project is small, the cost to de-energize and ground the lines can be excessive in comparison to the cost of the job.
Option 2 — Maintain 20-foot clearance
This option requires a minimum 20-foot clearance be maintained at all times. (If the work requires a closer approach than 20 feet, then Option 3 must be used.) The advantage of using this option is that employers don’t have to determine the exact voltage of the power lines; they only have to determine it is not more than 350kV.
To help make sure the 20-foot distance is not breached, the following precautions are required:
Option 3 — Follow Table A clearance
For this option, the employer must determine the power line’s voltage (by getting the voltage from the utility owner/operator), then determine whether any part of the crane, load line, or load (including the rigging and lifting accessories) could get closer to the power line than the minimum approach distance allowed in Table A.
When making this determination, assume the crane will be operated up to its maximum working radius when in the work zone, and comply with the minimum clearance distances in Table A. Note that, depending on the voltage, minimum clearance distances can be closer than the 20-foot clearance required for Option 1.
Table A — Minimum clearance distances | |
---|---|
Voltage (nominal, kV, alternating current) | Minimum clearance distance (feet) |
up to 50 | 10 |
over 50 to 200 | 15 |
over 200 to 350 | 20 |
over 350 to 500 | 25 |
over 500 to 750 | 35 |
over 750 to 1,000 | 45 |
over 1,000 | As established by the utility owner/operator or a registered professional engineer who is a qualified person with respect to electrical power transmission and distribution. |
The utility owner/operator must provide the requested voltage information within two days of the request.
If the crane could get closer to the power line than the minimum approach distance allowed in Table A, the same precautions mentioned in Option 2 apply.
There are requirements in place to protect employees from contact with power lines. The requirements consist of prerequisites and criteria that apply when work must be done closer than the minimum clearance distance specified in Table A of 1926.1408.
Working closer than the minimum approach distance allowed in Table A is highly discouraged.
However, there is an exception if the following three requirements are met:
The next step is to have a planning meeting that includes the employer and utility owner/operator to determine the procedures that will be followed to prevent electrical contact and electrocution. At a minimum, there are 12 procedures that must be included, per 1926.1410(d)(1) through (d)(12), and these procedures must be documented and immediately available on-site.
Traveling under or near power lines with no load
Equipment traveling under or near power lines with no load is covered at 1926.1411. The minimum clearance distances in Table T must be maintained. For traveling in poor visibility, a dedicated spotter should be used if needed, along with additional precautions.
When cranes are operating near overhead power lines, the crane, load line, or load could come into contact with the lines. If that happens, the electric current will pass through the equipment to the ground.
Anyone touching the crane in this situation will act as a ground, and the electric current will pass through the person. Even if the person doesn’t touch the equipment, the ground near the crane will be energized and present an electrocution hazard.
The Occupational Safety & Health Association (OSHA) refers to this hazard as “touch potential.” Touch potential is the voltage between the energized object and the feet of a person in contact with the object. It is equal to the difference in voltage between the object and a point some distance away.
Note that the touch potential could be nearly the full voltage across the grounded object if that object is grounded at a point remote from the place where the person is in contact with it. For example, a crane that was grounded to the system neutral and that contacted an energized line would expose any person in contact with the crane, or its uninsulated load line, to a touch potential nearly equal to the full voltage of the power line.
People should avoid approaching or coming into contact with any equipment that is operating, or any load being moved, near power lines.
If a crane comes into contact with a power line, the current will pass through the equipment to the ground. This unintentional grounding, more commonly known as a ground fault, enables voltages to be impressed on the “grounded” object that is faulting the line. A person could be at risk of injury during a fault simply by standing near the grounding point.
The Occupational Safety & Health Association (OSHA) refers to this hazard as “step potential.” Step potential is the voltage difference between the two feet of a person standing near an energized grounded object. It is equal to the difference in voltage, given by the voltage distribution curve, between two points at different distances from the electrode.
OSHA recommends that anyone who is not directly involved in the operation being performed should keep away from areas where hazardous step or touch potentials could arise. Anyone on the ground in the vicinity of transmission structures should stay at a distance where step voltages would be insufficient to cause injury.
A common method of grounding, which the Occupational Safety & Health Association (OSHA) recommends in 1926 Subpart O — Motorized Vehicles, Mechanical Equipment, and Marine Operations for work near an electrical charge, includes:
It’s important to understand that work being performed near transmitter towers or power lines (where an electrical charge can be induced in the equipment or materials being handled) must have precautionary measures implemented to dissipate induced voltages before work is performed. Being aware of the limitations of grounding is key.
Limitations of grounding
According to the preamble to Subpart CC (page 47958 of the Federal Register dated August 9, 2010), “OSHA is aware that employees are exposed to serious electric shock hazards when they are attaching grounds in accordance with 1926.1408(f). For example, when attaching the rigging to the load or the ground to the crane, the crane and load will be energized.
“OSHA views this condition as a recognized hazard and expects employers to ensure that employees are adequately protected when they are attaching grounds. Employers who fail to properly protect their employees in this regard will, in appropriate circumstances, be subject to citation under the General Duty Clause (sec. 5(a)(1)) of the OSH Act.”
Recommended evacuation procedures
Deciding whether to remain inside the cab or evacuate after power-line contact is important, especially where there is an imminent danger of fire, explosion, or other emergency. According to OSHA, to protect crane operators against electrical shock, the following procedures are recommended:
It’s important to understand that insulating links, proximity alarms, and range control (and similar) devices all have their limitations.
Insulating links
Insulating links serve a dual purpose. They protect a rigger who is handling the load if the equipment upstream of the link makes electrical contact with a power line. They also protect employees who are upstream of the insulating link if the load makes electrical contact with a power line.
The workers who are at the greatest risk of electrocution — the riggers who handle the load — are also protected by the requirement for nonconductive tag lines.
The insulating link option that is available under 1926.1408(b)(4)(v) would not protect against encroachment (certainly a limitation), but it would provide protection to employees handling the load in the event that encroachment did occur.
Insulating links must be installed between the end of the load line and the load. When so installed, these prevent the load from becoming energized in the event the load line or other part of the equipment makes electrical contact with a power line.
Preventing the load from becoming energized helps protect riggers, who often guide crane loads manually and who are at a high risk of being electrocuted if a load becomes energized. For more information on insulating links, including the phase-in period for these devices, see 1926.1408(b)(4).
Proximity alarms
A proximity alarm is a device that warns of the equipment coming near a power line. The device must be listed, labeled, or accepted by an Occupational Safety & Health Association (OSHA) Nationally Recognized Testing Laboratory. The limitations of a proximity alarm include not being operational, or effective against electrocution, during certain phases of the assembly or disassembly process of certain types of cranes.
Range control devices
A range control warning device is a device that can be set by an equipment operator to warn that the boom or jib tip is at a certain plane or multiple planes. The device must be set to alert the operator in time to prevent the boom, load line, or load (whichever is closest to the power line) from breaching the trigger distance.
As a practical matter, the device has to be set to sound the warning before the trigger distance is reached, since the operator will need some time to react and to account for the momentum of the equipment, load line, and load.
Some mobile crane accidents happen because of improper assembly and disassembly of the crane on the jobsite. Most of these accidents could be avoided by following the crane manufacturer’s requirements for assembly/disassembly (A/D). That’s why the Occupational Safety & Health Association (OSHA) requires the employer to comply with all manufacturer prohibitions applicable to assembly and disassembly, and use either:
Manufacturer procedures are generally the first choice. Employer procedures may be used only where the employer can demonstrate that the procedures used do the following:
Employer procedures must be developed by a qualified person.
Synthetic slings are an exception. Employer procedures can’t be used during rigging if the employer uses synthetic slings. Rather, the synthetic sling manufacturer’s instructions, limitations, specifications, and recommendations must be followed.
Proper assembly procedures
Accidents during A/D are often caused by:
The details of these tasks, and the location of danger areas that workers need to keep out of, often vary from one machine to another. The A/D director is responsible for making sure that the crew members know this essential information before starting the A/D process.
Crew instructions
Before beginning A/D operations, the A/D director must make sure that the crew members understand:
Before a crew member takes on a different task, or when adding new personnel during the A/D operations, the crew instruction requirements listed above must be met. Crew instructions must be given first.
Capacity limits
Rated capacity limits must not be exceeded for loads imposed on the equipment, equipment components (including rigging), lifting lugs, and equipment accessories. This prohibition applies during all phases of A/D.
In some cases, the crane being assembled is used to install its own counterweights (which can create a capacity limit risk). Early in this process, when few counterweights are in place, the crane’s capacity will be so limited that swinging beyond a certain point, or booming out beyond a certain point, may cause it to overturn.
Note that where an assist crane is being used during the A/D of another crane/derrick, the requirements for rated capacity during operations must be met.
Proper blocking plays an important role in assembly/disassembly (A/D) safety. Blocking is used in a variety of circumstances to compensate for minor ground sloping and to enhance stability by spreading out the area over which forces from the load are transferred to the ground. It is used to help support assembled equipment (usually placed under outrigger pads) and during A/D to support components.
Blocking that is undersized, insufficient in type or number, in poor condition, and/or stacked in an unstable manner could lead to a failure of support and unplanned movement or collapse of the equipment or component.
The Occupational Safety & Health Association (OSHA) defines “blocking” (also referred to as “cribbing”) as “wood or other material used to support equipment or a component and distribute loads to the ground…typically used to support latticed boom sections during assembly/disassembly and under outrigger floats.” (1926.1401)
When blocking is used to support lattice booms or lattice components, the failure to place it in the correct location could have several dangerous consequences. For example, incorrect placement could cause part of the lattice boom/component to bear too much force and damage it.
Damage to the boom/component could compromise structural integrity and, in some cases, may not be immediately noticed. If the assembly process were to continue, the boom/component could fail.
Improper blocking location may also result in a failure to provide adequate support of the boom/component. One example is blocking used to provide support to a boom section, such as after pins are removed. If the blocking is in the wrong place, once the pins are removed, unplanned movement or collapse could result.
OSHA’s regulatory requirement is stated simply as, “The size, amount, condition and method of stacking the blocking must be sufficient to sustain the loads and maintain stability.” (1926.1404)
An assist crane is a crane used to assist in assembling or disassembling a crane. When using an assist crane, the loads that will be imposed on the assist crane at each phase of assembly/disassembly (A/D) must be verified (before A/D begins) with at least one of the following methods:
At times, resulting loads on assist cranes during the A/D process are not properly anticipated. For example, when a boom is being disassembled in a cantilevered position, an assist crane is sometimes used to help support the boom. In some instances, the load is within the assist crane’s rated capacity prior to pin removal but exceeds its rated capacity once the pins are removed, causing a collapse.
The point(s) of attachment of rigging to a boom (or boom sections, or jib or jib sections) must be suitable for preventing structural damage and allowing safe handling of these components. Damage could compromise structural integrity and, in some cases, may not be immediately noticed. If that component is used, the boom/component could fail.
Safe handling of the boom/jib or boom/jib sections requires using pick points that will result in the boom/section being at the intended angle (90 degrees to the load line or some other intended angle) when hoisted.
For example, if the boom/section is intended to be horizontal, and only one pick point is going to be used, the pick point must coincide with the center of gravity. If the boom/section is intended to be at some other angle, a pick point would need to be identified that would generate that angle. Failing to do this could cause unintended movement during connecting or disconnecting the boom/section.
Often the method used for maintaining stability during assembly/disassembly (A/D) depends on supporting or rigging a component (or set of components) so that it remains balanced throughout the lift. In such instances, the A/D director is required to identify the center of gravity of the load.
One example of a situation where it would be necessary to identify the center of gravity is if the A/D crew is relying on an assist crane to suspend a component in a horizontal position. In this case, the center of gravity must be identified in order to correctly install the rigging.
If the center of gravity is not identified before installing the rigging, employees might try to compensate by riding on the section/component while it is being moved into place, which is quite dangerous. Also, in such a situation, if the component gets “hung up,” it can move unexpectedly when freed.
Some methods for maintaining stability do not depend on rigging or supporting the component to attain horizontal balance. For example, if two adjoining sections of a boom are being disconnected from each other, and both sections are supported at all four end points by blocking, then identifying the center of gravity may not be necessary.
There may be instances where the A/D method being used requires the identification of the center of gravity, but the employer can’t get sufficient information to make that identification. If the center of gravity cannot be identified, precautions must be taken to prevent unintended dangerous movement.
The boom sections, boom suspension systems (such as gantry A-frames and jib struts), and components must be rigged or supported to maintain stability upon the removal of the pins.
The Occupational Safety & Health Association (OSHA) defines “boom suspension systems” as “a system of pendants, running ropes, sheaves, and other hardware which supports the boom tip and controls the boom angle.” (1926.1401)
The process of pin removal is particularly hazardous. Potential energy in these sections, systems, and components can be released suddenly during pin removal, resulting in unanticipated movement ranging from shifting to collapse. Even small movements can result in injury, including amputations; larger movements and collapses can cause fatal injuries.
The key to preventing these injuries and fatalities is ensuring that the sections/components remain stable upon the removal of the pins. Instability can have a variety of causes, including improper A/D sequencing, improper rigging, incorrectly designed support, blocking failures, and ground compression.
The assembly/disassembly (A/D) director supervising the A/D operation must address known hazards associated with the operation and come up with methods to protect the employees from those hazards. The A/D director must consider each hazard, determine the appropriate means of addressing it, and oversee the implementation of that method.
Snagging
Suspension ropes and pendants must not be allowed to catch on the boom or jib connection pins or cotter pins (including keepers and locking pins). This could damage the cables or other components and result in injury.
Pendant cables are typically used in a latticed boom crane system to easily change the length of the boom suspension system without completely changing the rope on the drum when the boom length is increased or decreased. In many cases, the pendant cables hang alongside the boom and may get caught (snagged) on the pins, bolts, or keepers as the operator raises the boom.
If snagging occurs, the cables can be damaged, or the boom may rise then drop suddenly as a snagged cable releases from the pin. This can result in shock loading and damage to cables and components.
Counterweight strikes
Counterweights are usually large, heavy plates made of steel and/or concrete. The A/D process typically involves the installation and removal of counterweights.
During the installation/removal process, employees tend to be in close proximity to counterweights. If a counterweight sways as it’s being installed or removed, an employee can be struck by it or crushed between it and the crane.
The A/D director must address this aspect of the hazard, such as by taking steps to have the operator minimize the amount of sway and by positioning the employees to minimize their hazard exposure.
Additionally, after the counterweights are installed, the crane may have to swing to complete the boom assembly. The A/D director is required to address this aspect of the hazard as well, such as through the proper positioning of employees and enhancing their awareness of the counterweight swing zone so that they will avoid being struck or crushed.
Loss of backward stability
There are three points during the A/D process at which there is a heightened risk of loss of backward stability. These are:
Therefore, before any of these occur, the A/D director is required to consider whether precautions need to be instituted to ensure that backward stability is maintained.
One common hazard is an operator swinging or moving the crane when assembly/disassembly (A/D) personnel are in a crush/caught-in-between zone and out of the operator’s view. An effective and practical means of preventing these accidents is through a communication procedure that provides key information to, and coordination between, the operator and these workers.
That’s why the operator must be informed when a crew member is going to a location in, on, under, or near the equipment or load that is out of view of the operator, and where the movement of the equipment could injure the worker.
When the operator knows that a crew member went to a hazardous location, the operator must not move any part of the equipment (or load) until the operator is informed via a prearranged system of communication that the crew member is in a safe position.
An example of such a system would be the use of a signal person who gives an all-clear signal to the operator once the signal person sees that the employee has exited the hazard area.
Another example would be where the employee in the hazard area is equipped with a portable air horn and, in accordance with a prearranged horn signal system, sounds an appropriate signal to the operator that the employee has exited the hazard area. To be effective, the prearranged signal system needs to be designed so that this all-clear signal could not be confused with a horn signal from some other employee for another purpose.
Boom hoist brake failure is a hazard that can be present during both assembly and disassembly, although it is more typically an assembly hazard. In many older cranes, the boom hoist brake mechanism has an external or internal mechanical brake band that operates by pressing against the hoist drum. As the configuration of the crane changes and, for example, more boom is added, this type of boom hoist brake may slip unless it has been adjusted to hold the extra weight.
The inability of an unadjusted brake to hold the increased load will not be evident until the additional boom section has been added and the operator attempts to rely on the brake in a subsequent phase of the operation. If the operator does not first raise the boom a small amount after the section has been added (with the crew clear of the boom) to test the brake, employees could be injured later in the process when the operator manipulates the boom and is unexpectedly unable to brake it.
In many cases, if the brake is insufficient, an adjustment to it will correct the problem. If it remains insufficient, the employer is required to use a boom hoist pawl, other locking device, backup braking device, or another method of preventing dangerous boom movement (such as blocking or using an assist crane to support the load) from a boom hoist brake failure.
The brake test needs to be performed before anyone relies on the brake. It needs to accurately account for the loads that will be placed on the brake.
The assembly/disassembly (A/D) director is required to address hazards caused by wind speed and weather to ensure that the safe A/D of the equipment is not compromised. Selecting any one particular speed as a maximum would be arbitrary because of the variety of factors involved.
For example:
The A/D director must determine the maximum safe wind speed under the circumstances.
Other weather conditions that can affect the safety of A/D include, for example, ice accumulation on crane components. Ice can both add to the weight of the components and make surfaces on which employees work slippery and dangerous. The A/D director must address weather conditions that affect the safety of the operation.
One hazard an employee may encounter is removing pins while under the boom (and jib or similar components). If the wrong pins are removed while employees are under the component, it can move or collapse.
Even when pins are removed in the correct order, there may be unexpected stresses in the component, such as stored kinetic energy, that may not be apparent until that energy is released upon the removal of the pin. This can result in unexpected movement of the component.
Removing pins while under the boom should be avoided when possible. There is an exception: where the employer demonstrates that site constraints require one or more employees to be under the boom, jib, or other components when pins (or similar devices) are being removed, the assembly/disassembly (A/D) director must implement procedures that minimize the risk of unintended dangerous movement and minimize the duration and extent of exposure under the boom.
Sample scenario for the exception
In this scenario, there is a boom that cannot be disassembled on the ground because of aboveground piping (as might be found, for example, in an oil refinery) that precludes lowering the boom to the ground. The boom must therefore be disassembled in the air, and the employees who remove the pins must perform that work from an aerial lift whose base is positioned on one side (the near side) of the boom.
To gain access to the pins on the far side, the aerial lift basket must move under the boom, since, due to lack of room, the aerial lift cannot be repositioned on the far side.
To minimize the risk of unintended dangerous movement while the pins are removed, the A/D director uses an assist crane that is rigged to support the boom section that is being detached, using particular care to ensure that the section end that is near the employee(s) removing the pins is well supported.
The duration and extent of exposure is minimized by removing the far side pins first, moving the aerial lift basket as soon as possible to the near side so that the employees are no longer under the boom, and then removing the near side pins.
To minimize risks on the jobsite, employers in the construction industry using mobile cranes in the construction industry must address the following issues.
Cantilevered boom sections
A common mistake in assembly/disassembly is cantilevering too much boom. When this is done, structural failure can occur in components such as the mast/gantry, boom sections, and lifting lugs.
Employees may be struck by falling components from this type of failure. To prevent accidents from cantilevering too much boom during assembly/disassembly, the manufacturer’s limitations on cantilevering must not be exceeded.
If the manufacturer’s limitations are not available, the employer is required to have a registered professional engineer (RPE) determine the appropriate limitations, and to abide by those limitations. The RPE’s determination must be in writing to ensure that the assessment has been done.
Weight of components
As with any load to be lifted by a crane/derrick, the weight of the components must be available to the operator so that the operator can determine if the lift can be performed within the crane/derrick’s capacity. This requirement applies irrespective of whether the component is being hoisted by the crane being assembled/disassembled or by an assist crane.
Manufacturer prohibitions
Manufacturers’ prohibitions always take precedence. A prohibition specified by the manufacturer is a clear sign that if it is not heeded, a significant hazard would likely be created.
An employer would be able to choose to use either manufacturer assembly/disassembly procedures or the workplace’s own, as long as the procedures meet the requirements. However, in either case, the manufacturer prohibitions regarding assembly or disassembly would need to be met.
Shipping pins
Reusable shipping pins, straps, links, and similar equipment must be removed. Once removed, they must be stowed or otherwise stored so that they do not present a falling object hazard.
Being properly stowed might include being placed in a special hole or bracket designed to keep the item from being dislodged. Storage on the equipment could include placing them in an equipment box in the cab.
Pile driving
Equipment used in pile driving operations must not have a jib attached. The constant pounding of the pile driving hammer and the sometimes-rapid descent of the pile causes the boom to bounce.
If a jib were installed on the tip, as the boom bounces the jib could be thrown backward against its stops, which would likely cause structural damage to the boom. The damage could cause the boom to immediately fail or could diminish its capacity.
Rigging work
When rigging is used for assembly/disassembly, the employer must make sure that:
To determine the proper selection of components and proper configurations, employers should consult the manufacturer’s instructions, limitations, and specifications. Regarding component selection, hazards are associated with the use of components that the manufacturer neither intended nor planned for incorporation into the equipment. Such components could adversely affect the capacity and performance of the crane/derrick, make the manufacturer’s specifications (including the load chart) and instructions inapplicable, and adversely affect other components on the crane/derrick.
Similar hazards are posed by configuring the crane/derrick in a manner that does not accord with the manufacturer’s instructions, limitations, and specifications. This could occur when trucks carrying boom sections arrive out of sequence.
To save time, some employers assemble the sections in the order in which they arrive rather than waiting for the correct section. This results in a crane/derrick configured differently than intended by the manufacturer. Because the crane/derrick is designed and tested as a unit, the failure to configure the crane/derrick as the manufacturer had intended could present the same hazards as those described above for improper component selection.
There may be instances when the crane manufacturer no longer exists and the employer can no longer obtain the manufacturer’s instructions, limitations, and specifications regarding the selection of components and configuration of the equipment. In such cases, a registered professional engineer familiar with the type of equipment involved must approve, in writing, the component selection and configuration.
Section 1926.1434 allows cranes/derricks to be modified under certain circumstances. To the extent a crane/derrick is modified in accordance with this section, the employer cannot be required to follow the manufacturer’s original instructions, limitations, and specifications regarding component selection and configuration regarding those modifications. Instead, the employer is required to follow the component selection and configuration requirements approved according to 1926.1434.
Finally, the equipment must be inspected after assembly has been completed to ensure that the component selection and configuration are correct.
Outriggers are designed to take all load off the tires. Stabilizers are designed to relieve some, but not all, of the sprung weight for the purpose of increasing the stability of the vehicle.
Any time outriggers or stabilizers are used, all of the following requirements must be met (except as otherwise indicated):
The work area is the accessible areas in which the equipment’s rotating superstructure (whether permanently or temporarily mounted) poses a reasonably foreseeable risk of:
Hazards of rotating superstructures
The rotation of a crane’s superstructure can cause serious injury and death to employees working near the crane. Specifically, there are two hazards employees need to be aware of:
The employer is required to erect and maintain control lines, warning lines, railings, or similar barriers to mark the boundaries of the hazard areas. One type of barrier that is often used is attached directly to the crane and moves with the equipment.
There is an exception, and that is when the employer can demonstrate that it is feasible to erect such barriers on neither the ground nor the equipment. In that case, the hazard areas must be clearly marked by a combination of warning signs (such as “Danger — Swing/Crush Zone”) and high-visibility markings on the equipment that identify the hazard areas. In addition, the employer must train each employee to understand what these markings signify.
Cranes working near each other
If there are several cranes working near each other, and if any part of a crane/derrick is within the working radius of another crane/derrick, the controlling entity (CE) must institute a system to coordinate operations. If there is no CE, the employer (if there is only one employer operating the multiple pieces of equipment) or employers must devise and institute such a system.
There may be times when an employee must go into part of the crane’s swing hazard area that is out of sight of the crane operator. Before doing so, the crane operator must be informed that someone is entering the swing hazard area.
Once the crane operator has been informed that an employee is within the swing hazard area, the operator must not rotate the superstructure until the operator is informed, according to a pre-arranged system of communication, that the employee is in a safe position.
An example of such a communication system would be the use of a signal person who gives an all-clear signal to the operator once the signal person sees that the employee has exited the hazard area. Another example would be where the employee in the hazard area is equipped with a portable air horn and, in accordance with a pre-arranged horn signal system, sounds an appropriate signal to the operator that the employee has exited the hazard area.
To be effective, the pre-arranged signal system needs to be designed so that this all-clear signal could not be confused with a horn signal from some other employee for another purpose.
The Occupational Safety & Health Association’s (OSHA) 29 CFR 1926 Subpart CC has specific requirements for keeping employees clear of the load:
OSHA defines “fall zone” as the area (including but not limited to the area directly beneath the load) in which it is reasonably foreseeable that partially or completely suspended materials could fall in the event of an accident. For example, if wind is causing the load to swing, the employer would need to consider the breadth of the swinging (or potential swinging) in determining the extent of the fall zone.
Another example is where a bundle of materials is suspended and some loose materials at the top of the bundle may slide off sideways. In such a case, those materials could foreseeably fall outside the area directly beneath the load.
When employees are engaged in hooking, unhooking, or guiding the load, or in the initial connection of a load to a component or structure, and are within the fall zone, all of the following criteria must be met:
When a load is being landed, only employees needed to receive a load are permitted to be within the fall zone. An employee receiving a load will typically need to be within the fall zone when the load is being landed because that is the time when the load needs to be guided to a specific landing point.
In tilt-up and tilt-down operations, one end of a component, such as a precast panel, is either:
Note: These requirements do not apply when receiving a load; they only apply during tilt-up and tilt-down operations.
During a tilt-up or tilt-down operation:
An employee is considered “essential to the operation” if the employee is conducting one of the following operations and the employer can demonstrate that it’s infeasible to perform that operation from outside the fall zone:
The requirements for signs, signals, and markings in the Occupational Safety & Health Association’s (OSHA) 29 CFR 1926 Subpart CC include the following.
Leaving the equipment unattended — Barricades/Caution lines and notices
When the equipment is left unattended, barricades or caution lines and notices must be erected to prevent all employees from entering the fall zone. No employees are permitted in the fall zone when the equipment is unattended, including those who are:
Out of service — Tag-out
When the employer has taken the equipment out of service, a tag must be placed in the cab stating that the equipment is out of service and is not to be used. When the employer has taken a crane function(s) out of service, a tag must be placed in a conspicuous position stating that the function is out of service and is not to be used.
If there is a warning (tag-out or maintenance/do not operate) sign on:
then the operator must not activate the switch or start the equipment until the sign has been removed by a person authorized to remove it, or until the operator has verified that:
A study of crane-related fatalities in the U.S. construction industry found that 2 percent of the fatalities resulted from falls. Falls from cranes, particularly when the operator is entering or leaving the crane, also cause numerous non-fatal injuries to construction workers.
Training
Employers must train each employee who may be exposed to fall hazards while on, or hoisted by, equipment covered by the Occupational Safety & Health Association’s (OSHA) 29 CFR 1926 Subpart CC. The training must consist of:
Types of fall protection
“Fall protection equipment” is defined as “guardrail systems, safety net systems, personal fall arrest systems, positioning device systems, or fall restraint systems.” (1926.760)
“Fall restraint system” is defined as “a fall protection system that prevents the user from falling any distance. The system is comprised of either a body belt or body harness, along with an anchorage, connectors and other necessary equipment. The other components typically include a lanyard and may also include a lifeline and other devices.” (1926.751)
The types of fall protection required for cranes are the same fall protection equipment required under other OSHA standards.
Personal fall arrest equipment and use
Personal fall arrest system components must be used in personal fall arrest and fall restraint systems and must conform to the criteria in 1926.502(d), except that 1926.502(d)(15) does not apply to components used in personal fall arrest and fall restraint systems. Either body belts or body harnesses must be used in personal fall arrest and fall restraint systems.
There is a required use exception, namely that operators do not need to be tied off when moving to and from their crane cabs.
Fall protection is also not required for employees on decks, since that equipment is typically designed so that employees are not exposed to a fall hazard.
The following information is for crane manufacturers and for employers. Employees should also be aware of these requirements.
Existing equipment manufactured before November 8, 2011, does not have to be retrofitted with new steps, handholds, and railings simply because the existing design may vary from what is required in Subpart CC.
For non-assembly/disassembly work, employees must use provided fall protection equipment when they are on a walking/working surface with an unprotected side or edge more than 6 feet above a lower level when moving point-to-point (when the employee is in the process of going to or from a workstation).
The following table describes point-to-point movements requiring fall protection.
On non-lattice booms (whether horizontal or not horizontal) | Non-lattice booms generally present more hazards (than lattice booms) to workers who must walk them to reach other work areas, devices, and equipment. Non-lattice booms are typically extensible booms, and the surface is usually oily from the hydraulic mechanisms. |
On lattice booms that are not horizontal | An employee may need to move point-to-point on a lattice boom to inspect a part that may need repair, or to make the repair. In many cases, the boom may not be horizontal, since space limitations can make it difficult to lower the boom to perform the work. Since the boom would be elevated, there would usually be a point on the boom above the level of the worker’s feet to attach a lanyard. |
On horizontal lattice booms where the fall distance is 15 feet or more | The 15-foot minimum distance is used because a personal fall arrest system tied off at the level of the employee’s feet, with a lanyard long enough to allow the employee the range of movement necessary for this work, might not prevent the employee from falling to the next lower level. |
Employees must also use fall protection equipment when they are on a walking/working surface with an unprotected side or edge more than 6 feet above a lower level and not moving point-to-point. For example, if an employee is stationary at a workstation on any part of the equipment (including the boom, of any type), the employee needs fall protection, except when the employee is:
Assembly/Disassembly work
For assembly/disassembly (A/D) work, employees must use provided fall protection equipment when they are on a walking/working surface with an unprotected side or edge more than 15 feet above a lower level, except when the employee is
The Occupational Safety & Health Association (OSHA) has a new enforcement policy that excludes monorail hoists from the requirements of Subpart CC — Cranes and Derricks in Construction, as long as employers meet other OSHA requirements.
The following is from an OSHA Memorandum issued June 30, 2017.
“The scope of Cranes and Derricks in Construction (the cranes standard, 29 CFR Part 1926, subpart CC) includes a functional definition for the equipment covered. The standard applies to ‘power-operated equipment, when used in construction, that can hoist, lower, and horizontally move a suspended load.’ (29 CFR 1926.1400[a]). Monorail hoists are not explicitly excluded from the scope of the rule, and OSHA has issued several letters of interpretation confirming the crane standard’s coverage of specific monorail hoists in certain construction operations.
“As a number of stakeholders have pointed out, the standard is not a perfect fit for monorail hoists, and OSHA intends to consider rulemaking options to address this issue. The purpose of this memorandum is to announce a temporary enforcement policy pending the resolution of that rulemaking process.
“Most monorail hoist systems have a completely fixed monorail (I-beam). When used in construction, these hoisting systems are typically mounted on equipment such as work vehicles, trailers, and scaffolding systems. The monorails can be extended and contracted in only a fixed horizontal direction to hoist materials and can only hoist them as high as the monorail. Some examples of materials commonly lifted and placed by monorail hoists during construction are precast concrete components (septic tanks, storm drain and sewer conduits, vaults, etc.); storage tanks (propane, oil, etc.); mechanical components (engines, commercial generators, etc.); trade specific components (electrical transformers, industrial spooled materials, sewer lids, etc.); and temporary storage units.
“Monorail hoists present unique issues. Many monorail hoist manufacturers do not design their systems to meet any particular criteria recommended in consensus standards, though the designs of their hoisting mechanisms most resemble those of overhead hoists covered by ASME 830.172015 (Cranes and Monorails (With Underhung Trolley or Bridge)).
“Stakeholders have pointed out that a number of the provisions of the crane standard add very little protection when these monorail hoists are used. For example, the stakeholders have told OSHA that because these monorails are fixed such that they do not angle up or down, the equipment does not warrant the elevated level of protections from power-line contact required by the crane standard. They also note that monorails cannot boom out significantly beyond the wheelbase of a vehicle or the base of its supporting structure, and thus the hoisting equipment does not pose the dangerous cantilevering and stability hazards that are addressed by requirements of the crane standard.
“Furthermore, they assert that there is no need for specific protections from hazards posed by booming out loads, boom free fall, equipment swing radius, or any crane-related hazards that would necessitate the use of devices like level indicators, boom/jib stops, boom/jib limiting devices, boom length/radius indicators, and drum hoist rotation indicators.
“Finally, stakeholders have pointed out that the loads handled by monorail hoists are not heavy enough to trigger the need for a load weighing device or the use of load charts to prevent overloading and tipping the hosting equipment.
“However, it is clear that monorail and overhead hoist systems present recognized workplace hazards, including those addressed by 29 CFR 1926.554 (Overhead hoists), ASME B30. l 7, and various manufacturers’ recommendations. For the reasons discussed above, and until the application of the cranes standard to monorail hoists is revisited through rulemaking, OSHA intends to exercise its enforcement discretion by not citing employers for failing to achieve full compliance with the cranes standard when monorail hoists are used, if the following conditions are met to protect employees:
“Should an employer operating such equipment fail to comply fully with all of the requirements described, the requirements of the crane standard would apply.”
An aerial lift is any vehicle-mounted device used to elevate personnel, including:
Aerial lifts have replaced ladders and scaffolding on many jobsites due to their mobility and flexibility. They may be made of metal, fiberglass-reinforced plastic, or other materials. They may be powered or manually operated and are considered to be aerial lifts whether or not they can rotate around a primarily vertical axis.
Scope/who must comply
For general industry (i.e., non-construction) work, the Occupational Safety & Health Association (OSHA) only has a specific requirement for vehicle-mounted elevating and rotating work platforms, such as bucket trucks and smaller mobile, extensible boom lifts. This requirement is contained in 29 CFR 1910.67.
This regulation does not cover order pickers, scissor lifts, or personnel platforms attached to a forklift.
Hazards
The following hazards, among others, can lead to personal injury or death:
Training
Only trained and authorized persons are allowed to operate an aerial lift. Training should include:
Workers should be retrained if any of the following conditions occur:
Employers are also required to retrain workers who are observed operating an aerial lift improperly.
Prior to each work shift, workers should conduct a pre-start inspection to verify that the equipment and all its components are in safe operating condition. The inspection should follow manufacturer recommendations and include a check of/for:
If any component is defective, an aerial lift must not be operated until it is repaired by a qualified person. Defective aerial lifts must be removed from service (tagged out) until repairs are made.
Work zone inspection
Employers must ensure that work zones are inspected for hazards and take corrective actions to eliminate such hazards before and during operation of an aerial lift. Items to look for include:
Safety practices that must be observed when aerial lifts are used include fall protection, safe travel procedures, overhead protection, and maintaining stability of the aerial lift.
Fall protection
When using aerial lifts, workers should take the following precautions to prevent falls:
Operation when traveling
Workers should follow these rules for safe operation when traveling:
Overhead protection
Employees can be injured when contracting with overhead objects. To prevent this, they should follow these rules:
Aerial lift stability
To ensure the stability of the aerial lift and keep workers safe, these rules should be followed:
Aerial lifts used for construction tasks include the following types of vehicle-mounted aerial devices used to elevate personnel to jobsites above ground:
Scope/Who must comply
The Occupational Safety & Health Association (OSHA) considers scissor lifts to be mobile scaffolding. OSHA requires employers that use scaffolding to comply with 29 CFR 1926.453.
In addition, the training requirements at 29 CFR 1926.453 apply.
Hazards
The following hazards, among others, can lead to personal injury or death:
Training
All employees who work on an aerial lift must be trained by a person qualified to recognize the hazards associated with the type of scaffold used and to understand the procedures to control and minimize those hazards.
In addition, a competent person must train all employees who erect, disassemble, move, operate, repair, maintain, or inspect aerial lifts/scaffolds. Training must cover the nature of the hazards and the correct procedures for erecting, disassembling, moving, operating, repairing, inspecting, and maintaining the type of scaffold in use.
Other recommended training topics include the following:
Retraining
29 CFR 1926.454 requires retraining when:
Prior to each work shift, workers should conduct a pre-start inspection to verify that the equipment and all its components are in safe operating condition. The inspection should follow manufacturer recommendations and include a check of/for:
If any component is defective, an aerial lift must not be operated until it is repaired by a qualified person. Defective aerial lifts must be removed from service (tagged out) until repairs are made.
Employers must ensure that work zones are inspected for hazards and take corrective actions to eliminate such hazards before and during operation of an aerial lift. Items to look for include:
When using aerial lifts, workers should take the following precautions to prevent falls:
Workers should follow these rules for safe operation when traveling:
Employees can be injured when contracting with overhead objects. To prevent this, they should follow these rules:
To ensure the stability of the aerial lift and keep workers safe, these rules should be followed:
Scissor lifts provide a safe and reliable platform for workers to perform job tasks when used according to the manufacturer’s instructions. When not used properly, scissor lifts can present a serious hazard to workers.
Scissor lifts are different from aerial lifts because the lifting mechanism moves the work platform straight up and down using crossed beams that function in a scissor-like fashion. Scissor lifts present hazards similar to scaffolding when extended and stationary but using scissor lifts safely requires considering the equipment’s capabilities and limitations and safe practices.
Scope/Who must comply
All employers who have employees operating scissor lifts must comply. The Occupational Safety & Health Association (OSHA) considers scissor lifts to be mobile scaffolding. OSHA Letters of Interpretation dated 05/03/2001 and 10/23/2002 address and clarify this.
OSHA addresses mobile scaffolding at 29 CFR 1926.452(w).
Training
Employers must provide workers training on hazards, including how to work safely with or near scissor lifts, per 1926.454. Training must, at a minimum, include:
Over a one-year period, the Occupational Safety & Health Association (OSHA) investigated 10 preventable fatalities and more than 20 preventable injuries resulting from a variety of incidents involving scissor lifts. OSHA’s investigations found that most injuries and fatalities involving scissor lifts were the result of employers not addressing:
Employers need to assess the jobsite to identify all possible hazards in order to select the appropriate equipment for the task. Employers who use scissor lifts must evaluate and implement effective controls that address fall protection, stabilization, and positioning.
Only trained workers should be allowed to use scissor lifts, and employers should make sure that those workers show that they can use a scissor lift properly.
Safe scissor lift use includes properly maintaining the equipment, following the manufacturer’s instructions, providing workers with training and needed personal protective equipment (PPE), and implementing safe work practices.
Positioning the scissor lift to avoid crushing or electrocution hazards is important for safe use. Crushing hazards are present in workplaces with scissor lifts and may expose workers nearby, even those not working on the scissor lift. Scissor lifts present similar crushing hazards to vehicles and other mobile equipment at jobsites.
Employers should train workers to be watchful when:
Energized power lines
To safely use scissor lifts near energized power lines, the scissor lift must be positioned to avoid electrocution, arc flash, and thermal burns. Since electricity can arc or jump from the power line to the scissor lift or worker, electrocution can occur even if neither the scissor lift nor the worker touches the power line.
Employers should use the following work practices to ensure that scissor lifts are safely positioned:
Fall protection
Scissor lifts must have guardrails installed to prevent workers from falling (see 29 CFR 1926.451[g]). Employers should train workers to:
If all the manufacturer’s guardrails are in place, there is no requirement for having to wear a personal fall arrest harness and tie-off in the scissor lift.
Scissor lift stability
Employers should ensure that scissor lifts are stable and will not tip over or collapse. Some safe work practices to ensure safe, stable conditions for scissor lift use include:
Prior to each work shift, workers should conduct a pre-start inspection to verify that the equipment and all its components are in safe operating condition. The inspection should follow manufacturer recommendations and include a check of/for:
If any component is defective, a scissor lift must not be operated until it is repaired by a qualified person. Remove defective scissor lifts from service (tagged out) until repairs are made.
Work zone inspection
Employers must ensure that work zones are inspected for hazards and take corrective actions to eliminate such hazards before and during operation of a scissor lift. Items to look for include:
Maintenance
Employers must regularly maintain scissor lifts to ensure that they are safe to use (e.g., that the lifting mechanism will not collapse).
Manufacturers’ maintenance and inspection instructions should be followed. These will generally include how to:
The Occupational Safety & Health Association’s (OSHA) 29 CFR Subpart L standard sets performance-based criteria to protect employees from scaffold-related hazards such as falls, falling objects, structural instability, electrocution, and overloading. It also addresses training and various types of scaffolds, as well as falling object protection, ladders, weather conditions, aerial lifts, and stilts.
Scope/Who must comply
All employers performing construction work with scaffolds and general industry employers who use scaffolds in their production processes must comply. OSHA regulates scaffolding at 29 CFR 1926 Subpart L, 1926.450 through 1926.454 — Scaffolding.
Basic requirements
OSHA’s scaffolding standard has several key provisions that employers must follow:
Training
All employees must be trained by a qualified person to recognize the hazards associated with the type of scaffold being used and how to control or minimize those hazards. The training must include the following:
While “competent” and “qualified” ideally apply to everyone in a workplace, the Occupational Safety & Health Association (OSHA) specifies particular definitions for these adjectives and assigns different scaffolding responsibilities to each.
Competent person requirements
OSHA defines a competent person as “one who is capable of identifying existing and predictable hazards in the surroundings or working conditions, which are unsanitary, hazardous to employees, and who has authorization to take prompt corrective measures to eliminate them.” (1926.32)
The scaffolding standard requires a competent person to perform the following duties under these circumstances:
Qualified person requirements
OSHA defines a qualified person as “one who by possession of a recognized degree, certificate, or professional standing, or who by extensive knowledge, training, and experience has successfully demonstrated the ability to solve or resolve problems related to the subject matter, the work, or the project.” (1926.32)
The standard requires a qualified person to perform the following duties in these circumstances:
Registered professional engineer requirements
The standard requires a registered professional engineer to perform the following duties in these circumstances:
Each scaffold and scaffold component must support without failure its own weight and at least four times the maximum intended load applied or transmitted to it.
A qualified person must design the scaffolds, which are loaded in accordance with that design.
Scaffolds and scaffold components must not be loaded in excess of their maximum intended loads or rated capacities, whichever is less.
Load-carrying timber members should be construction-grade lumber of a minimum of 1,500 lb-f/in2.
Platform construction
Scaffold planking must be able to support, without failure, its own weight and at least four times the intended load.
Solid sawn wood, fabricated planks, and fabricated platforms may be used as scaffold planks following recommendations by the manufacturer or a lumber grading association or inspection agency.
Each scaffold platform and walkway must be at least 18 inches wide. When the work area is less than 18 inches wide, guardrails and/or personal fall arrest systems must be used.
Each platform must be planked and decked as fully as possible. The space between the platform and uprights cannot be more than 1 inch wide.
When side brackets or odd-shaped structures result in a wider opening between the platform and the uprights, this space must not exceed 9 inches.
Tables showing maximum permissible spans, rated load capacity, and nominal thickness are in Appendix A of the standard.
Platform safety procedures
The platform must not deflect more than 1/60 of the span when loaded.
The standard prohibits work on platforms cluttered with debris.
Employers are required to protect each employee on a scaffold more than 10 feet above a lower level from falling to that lower level.
To ensure adequate protection, guardrails must be installed along all open sides and ends before releasing the scaffold is released for use by employees, other than the erection and dismantling crews.
Guardrails are not required, however, when:
Steel or plastic banding must not be used as a top rail or a mid-rail.
Supported scaffolds are platforms supported by legs, outrigger beams, brackets, poles, uprights, posts, frames, or similar rigid support.
The structural members, poles, legs, posts, frames, and uprights must be plumb and braced to prevent swaying and displacement.
Supported scaffolds with a height-to-base-width ratio of more than 4:1 must be restrained by guying, tying, bracing, or an equivalent means.
To prevent tipping, either the manufacturers’ recommendation or the following placements must be used for guys, ties, and braces:
To ensure a firm foundation, supported scaffolds’ poles, legs, posts, frames, and uprights must bear on baseplates and mud sills or other adequate foundation.
Forklifts can support platforms only when the entire platform is attached to the fork and the forklift does not move horizontally when workers are on the platform.
Front-end loaders and similar equipment can support scaffold platforms only when they have been specifically designed by the manufacturer for such use.
There may be times when employers need to increase the height of employees on the supported scaffold. On a large-area scaffold, stilts may be used. When a guardrail system is used, the guardrail height must be increased in height corresponding to the height of the stilts.
The manufacturer must approve any alterations to the stilts.
Note: A large-area scaffold consists of a pole, tube, and coupler systems, or a fabricated frame scaffold erected over substantially the entire work area.
A suspension scaffold contains one or more platforms suspended by ropes or other non-rigid means from an overhead structure. Examples of suspension scaffolds include:
Some of the requirements for all types of suspension scaffolds:
The various components of suspension scaffold systems include counterweights, outrigger beams, tiebacks, suspension ropes, and scaffold hoists. These all must be installed, inspected, maintained, and used in compliance with regulations in order to minimize hazards.
Counterweights
Counterweights used to balance adjustable suspension scaffolds must be able to resist at least four times the tipping moment imposed by the scaffold operating at either the rated load of the hoist, or 1.5 times (minimum) the tipping moment imposed by the scaffold operating at the stall load of the hoist, whichever is greater.
Only those items specifically designed as counterweights must be used.
Counterweights used for suspended scaffolds must be made of materials that cannot be easily dislocated. Flowable material, such as sand or water, cannot be used.
Counterweights must be secured by mechanical means to the outrigger beams.
Vertical lifelines must not be fastened to counterweights.
Outrigger beams and tiebacks
Outrigger beams (thrustouts) are the structural members of a suspension or outrigger scaffold that provide support. They must be placed perpendicular to their bearing support.
Tiebacks must be secured to a structurally sound anchorage on the building or structure. Sound anchorages do not include standpipes, vents, other piping systems, or electrical conduit.
A single tieback must be installed perpendicular to the face of the building or structure. Two tiebacks installed at opposing angles are required when a perpendicular tieback cannot be installed.
Suspension ropes
The suspension ropes must be long enough to allow the scaffold to be lowered to the level below without the rope passing through the hoist, or the end of the rope configured to prevent the end from passing through the hoist.
The standard prohibits using repaired wire.
Drum hoists must contain no less than four wraps of the rope at the lowest point.
Employers must replace wire rope when any of the following conditions exist:
Suspension ropes supporting adjustable suspension scaffolds must be a diameter large enough to provide sufficient surface area for the functioning of brake and hoist mechanisms.
Suspension ropes must be shielded from heat-producing processes.
Scaffold hoists
Requirements for scaffold hoists include the following:
Welding from suspension scaffolds
Welding can be done from suspended scaffolds when:
Employers must provide access when the scaffold platforms are more than 2 feet above or below a point of access.
Direct access is acceptable when the scaffold is not more than 14 inches horizontally and not more than 24 inches vertically from the other surfaces.
The standard prohibits the use of cross braces as a means of access.
Several types of access are permitted:
Employees erecting and dismantling supported scaffolding must have a safe means of access provided after a competent person has determined the feasibility and analyzed the site conditions.
The standard requires specific clearance distances. The following table lists these distances:
Insulated lines voltage | Minimum distance | Alternatives |
---|---|---|
Less than 300 volts | 3 feet | |
300 volts to 50 kV | 10 feet | |
More than 50 kV | 10 feet plus 0.4 inches for each 1 kV over 50 kV | 2 times the length of the line insulator, but never less than 10 feet |
Uninsulated lines voltage | Minimum distance | Alternatives |
---|---|---|
Less than 50 kV | 10 feet | |
More than 50 kV | 10 feet plus 0.4 inches for each 1 kV over 50 kV | 2 times the length of the line insulator, but never less than 10 feet |
Fall protection includes guardrail systems and personal fall arrest systems. Personal fall arrest systems include harnesses, components of the harness/belt (such as D-rings), snap hooks, lifelines, and anchorage points.
Vertical or horizontal lifelines may be used.
Lifelines must be independent of support lines and suspension ropes and not attached to the same anchorage point as the support or suspension ropes.
When working from an aerial lift, users should attach the fall arrest system to the boom or basket.
Fall protection for specific types of scaffold
The following chart illustrates the type of fall protection required for specific scaffolds:
Type of scaffold | Fall protection required |
---|---|
Aerial lifts | Personal fall arrest system |
Boatswain’s chair | Personal fall arrest system |
Catenary scaffold | Personal fall arrest system |
Crawling board (chicken ladder) | Personal fall arrest system, or a guardrail system, or by a three quarter-inch diameter grabline or equivalent handhold securely fastened beside each crawling board |
Float scaffold | Personal fall arrest system |
Ladder jack scaffold | Personal fall arrest system |
Needle beam scaffold | Personal fall arrest system |
Self-contained scaffold | Both a personal adjustable scaffold arrest system and a guardrail system |
Single-point and two-point suspension scaffolds | Both a personal fall arrest system and a guardrail system |
Supported scaffold | Personal fall arrest system or guardrail system |
All other scaffolds not specified above | Personal fall arrest system or guardrail system that meets the required criteria |
Protection from overhead falling objects
To protect employees from falling hand tools, debris, and other small objects, employers should install toeboards, screens, guardrail systems, debris nets, catch platforms, canopy structures, or barricades. In addition, employees must wear hard hats.
A crane is designed to lift and lower a load and move it horizontally.
Overhead and gantry cranes have a horizontal bridge across which a trolley and hoist travel. Materials being moved by overhead cranes are attached to a hoisting mechanism on the trolley.
These cranes are useful in general machine shops, fabricating assemblies, printing operations, and warehousing. They can be purchased “as is” or custom-built by the manufacturer.
Scope/Who must comply
The Occupational Safety & Health Administration (OSHA) regulates overhead cranes at 29 CFR 1910.179.
The OSHA rule applies to overhead and gantry cranes, including semi-gantry, cantilever gantry, wall cranes, storage bridge cranes, and others having the same fundamental characteristics. These cranes are grouped because they all have trolleys and similar travel characteristics.
The rule covers the safe operation of overhead- and gantry-type cranes by setting down design criteria for manufacturers, as well as the safe procedures employers must follow pertaining to crane and rope inspections, equipment maintenance, load handling, and operator training.
Training
OSHA’s overhead crane standard does not provide much detail about crane operator training. The standard simply states at 1910.179(b)(8), “Only designated personnel shall be permitted to operate a crane covered by this section.” OSHA defines designated as “selected or assigned by the employer or the employer’s representative as being qualified to perform specific duties.”
OSHA clarifies in a November 8, 1999, Letter of Interpretation that the Agency would interpret “qualified” in light of operator-qualifications provisions of industry standards such as ANSI B30.2. In addition, although the 1910.178 powered industrial truck training requirements do not apply, employers may also find it useful to consult that standard when developing a training or evaluation program for “travel lift” operators.
In general, the standard requires covered employers to:
Whether the Occupational Safety & Health Administration (OSHA) requires a safety latch on a sling hook depends on the activity for which the sling is being used. While the standard for slings provides that “[s]lings shall be securely attached to their loads,” the section does not explicitly require that the hook be equipped with a safety latch.
Use of a hook with a safety latch would, of course, be one way of securely attaching a sling to its load. (Other standards, such as those for derricks, do include explicit requirements for latch-type hooks.)
In addition, OSHA often considers the provisions of industry consensus standards when evaluating whether a hazard is “recognized” and whether there is a feasible means of abating that hazard. One such provision that OSHA considers is ASME 30.2-2001, Overhead and Gantry Cranes, which does require “latch-equipped hooks” be used if practical and necessary for the lift.
Note: OSHA does not allow employees to tie off to the hook of an overhead crane. They address this issue in a still-valid letter dated April 4, 1993: “Work cannot be performed from a suspended load or hook ...”
In general, the standard requires covered employers to:
Whether the Occupational Safety & Health Administration (OSHA) requires a safety latch on a sling hook depends on the activity for which the sling is being used. While the standard for slings provides that “[s]lings shall be securely attached to their loads,” the section does not explicitly require that the hook be equipped with a safety latch.
Use of a hook with a safety latch would, of course, be one way of securely attaching a sling to its load. (Other standards, such as those for derricks, do include explicit requirements for latch-type hooks.)
In addition, OSHA often considers the provisions of industry consensus standards when evaluating whether a hazard is “recognized” and whether there is a feasible means of abating that hazard. One such provision that OSHA considers is ASME 30.2-2001, Overhead and Gantry Cranes, which does require “latch-equipped hooks” be used if practical and necessary for the lift.
Note: OSHA does not allow employees to tie off to the hook of an overhead crane. They address this issue in a still-valid letter dated April 4, 1993: “Work cannot be performed from a suspended load or hook ...”
A mobile crane is designed to lift and lower a load and move it horizontally. Mobile cranes come in all sizes so that the task of manipulating materials can be made safer and easier.
Scope/who must comply
The Occupational Safety & Health Association (OSHA) regulates mobile cranes at 29 CFR 1910.180 — Crawler locomotive and truck cranes.
The OSHA rule applies to crawler cranes, locomotive cranes, wheel-mounted cranes of both truck and self-propelled wheel type, and any variations thereof that retain the same fundamental characteristics. This includes only cranes of the above types, which are basically powered by internal combustion engines or electric motors and which utilize drums and ropes. Cranes designed for railway and automobile wreck clearances are excepted.
Training
OSHA’s mobile crane standard does not provide much detail about crane operator training. The standard simply states at 1910.180(b)(3), “Only designated personnel shall be permitted to operate a crane covered by this section.” OSHA defines designated as “selected or assigned by the employer or the employer’s representative as being qualified to perform specific duties.”
In general, the standard requires covered employers to:
Employers are responsible for ensuring that equipment is in working order and being used safely. They are required to:
When attaching the load, the user must ensure the hoist rope is not wrapped around the load. The load must be attached to the hook by means of slings or other approved devices.
Moving the load
The user should ensure the crane is level and is blocked properly where necessary.
The load must be secured and balanced in the sling or lifting device before it is lifted more than a few inches. Load (working) means the external load, in pounds, applied to the crane, including the weight of load-attaching equipment such as load blocks, shackles, and slings.
Before starting to hoist, the following conditions must be met:
During hoisting, the operator must ensure that:
Side loading of booms is limited to freely suspended loads. Cranes must not be used for dragging loads sideways.
No hoisting, lowering, swinging, or traveling shall be done while anyone is on the load or hook.
The operator must not carry loads over people.
On truck-mounted cranes, no loads shall be lifted over the front area except as approved by the crane manufacturer.
The operator shall test the brakes each time a load approaching the rated load is handled by raising it a few inches and applying the brakes.
Outriggers shall be used when the load to be handled at that particular radius exceeds the rated load without outriggers as given by the manufacturer for that crane. Outriggers are extendable or fixed metal arms, attached to the mounting base, which rest on supports at the outer ends.
Where floats are used, they shall be securely attached to the outriggers. Wood blocks used to support outriggers shall:
Neither the load nor the boom shall be lowered below the point where less than two full wraps of rope remain on their respective drums.
A designated person shall be responsible for determining and controlling safety before traveling a crane with load. Decisions such as position of load, boom location, ground support, travel route, and speed of movement are up to the designated person.
A crane with or without load shall not be traveled with the boom so high that it may bounce back over the cab.
Holding the load
Operators are not permitted to leave their position at the controls while the load is suspended.
No person should be permitted to stand or pass under a load on the hook.
If the load must remain suspended for any considerable length of time, the operator shall keep the drum from rotating in the lowering direction by activating the positive controllable means of the operator’s station.
Operations near overhead electric lines
If work is to be performed near overhead lines, the lines shall be deenergized and grounded, or other protective measures shall be provided before work is started. If the lines are to be deenergized, arrangements shall be made with the person or organization that operates or controls the electric circuits involved to deenergize and ground them.
If protective measures, such as guarding, isolating, or insulating, are provided, these precautions shall prevent employees from contacting such lines directly with any part of their body or indirectly through conductive materials, tools, or equipment.
In general, the standard requires covered employers to:
Employers are responsible for ensuring that equipment is in working order and being used safely. They are required to:
When attaching the load, the user must ensure the hoist rope is not wrapped around the load. The load must be attached to the hook by means of slings or other approved devices.
Moving the load
The user should ensure the crane is level and is blocked properly where necessary.
The load must be secured and balanced in the sling or lifting device before it is lifted more than a few inches. Load (working) means the external load, in pounds, applied to the crane, including the weight of load-attaching equipment such as load blocks, shackles, and slings.
Before starting to hoist, the following conditions must be met:
During hoisting, the operator must ensure that:
Side loading of booms is limited to freely suspended loads. Cranes must not be used for dragging loads sideways.
No hoisting, lowering, swinging, or traveling shall be done while anyone is on the load or hook.
The operator must not carry loads over people.
On truck-mounted cranes, no loads shall be lifted over the front area except as approved by the crane manufacturer.
The operator shall test the brakes each time a load approaching the rated load is handled by raising it a few inches and applying the brakes.
Outriggers shall be used when the load to be handled at that particular radius exceeds the rated load without outriggers as given by the manufacturer for that crane. Outriggers are extendable or fixed metal arms, attached to the mounting base, which rest on supports at the outer ends.
Where floats are used, they shall be securely attached to the outriggers. Wood blocks used to support outriggers shall:
Neither the load nor the boom shall be lowered below the point where less than two full wraps of rope remain on their respective drums.
A designated person shall be responsible for determining and controlling safety before traveling a crane with load. Decisions such as position of load, boom location, ground support, travel route, and speed of movement are up to the designated person.
A crane with or without load shall not be traveled with the boom so high that it may bounce back over the cab.
Holding the load
Operators are not permitted to leave their position at the controls while the load is suspended.
No person should be permitted to stand or pass under a load on the hook.
If the load must remain suspended for any considerable length of time, the operator shall keep the drum from rotating in the lowering direction by activating the positive controllable means of the operator’s station.
Operations near overhead electric lines
If work is to be performed near overhead lines, the lines shall be deenergized and grounded, or other protective measures shall be provided before work is started. If the lines are to be deenergized, arrangements shall be made with the person or organization that operates or controls the electric circuits involved to deenergize and ground them.
If protective measures, such as guarding, isolating, or insulating, are provided, these precautions shall prevent employees from contacting such lines directly with any part of their body or indirectly through conductive materials, tools, or equipment.
Employers are responsible for ensuring that equipment is in working order and being used safely. They are required to:
When attaching the load, the user must ensure the hoist rope is not wrapped around the load. The load must be attached to the hook by means of slings or other approved devices.
Moving the load
The user should ensure the crane is level and is blocked properly where necessary.
The load must be secured and balanced in the sling or lifting device before it is lifted more than a few inches. Load (working) means the external load, in pounds, applied to the crane, including the weight of load-attaching equipment such as load blocks, shackles, and slings.
Before starting to hoist, the following conditions must be met:
During hoisting, the operator must ensure that:
Side loading of booms is limited to freely suspended loads. Cranes must not be used for dragging loads sideways.
No hoisting, lowering, swinging, or traveling shall be done while anyone is on the load or hook.
The operator must not carry loads over people.
On truck-mounted cranes, no loads shall be lifted over the front area except as approved by the crane manufacturer.
The operator shall test the brakes each time a load approaching the rated load is handled by raising it a few inches and applying the brakes.
Outriggers shall be used when the load to be handled at that particular radius exceeds the rated load without outriggers as given by the manufacturer for that crane. Outriggers are extendable or fixed metal arms, attached to the mounting base, which rest on supports at the outer ends.
Where floats are used, they shall be securely attached to the outriggers. Wood blocks used to support outriggers shall:
Neither the load nor the boom shall be lowered below the point where less than two full wraps of rope remain on their respective drums.
A designated person shall be responsible for determining and controlling safety before traveling a crane with load. Decisions such as position of load, boom location, ground support, travel route, and speed of movement are up to the designated person.
A crane with or without load shall not be traveled with the boom so high that it may bounce back over the cab.
Holding the load
Operators are not permitted to leave their position at the controls while the load is suspended.
No person should be permitted to stand or pass under a load on the hook.
If the load must remain suspended for any considerable length of time, the operator shall keep the drum from rotating in the lowering direction by activating the positive controllable means of the operator’s station.
Operations near overhead electric lines
If work is to be performed near overhead lines, the lines shall be deenergized and grounded, or other protective measures shall be provided before work is started. If the lines are to be deenergized, arrangements shall be made with the person or organization that operates or controls the electric circuits involved to deenergize and ground them.
If protective measures, such as guarding, isolating, or insulating, are provided, these precautions shall prevent employees from contacting such lines directly with any part of their body or indirectly through conductive materials, tools, or equipment.
For employees who operate or work around cranes or derricks, it’s critical that they understand and comply with the necessary work practices established by their company to keep them safe from crane accidents.
Employees should have a basic understanding of electricity and the clearance distances necessary to minimize danger when working near power lines or other electrical sources. An understanding of the hazards associated with crane assembly/disassembly, rotating superstructures, energized equipment, and falls is also key to overall safety.
Scope/Who must comply
The Occupational Safety & Health Association (OSHA) regulates this at 29 CFR 1926 Subpart CC — Cranes and derricks in construction.
OSHA’s Subpart CC applies to power-operated equipment, when used in construction, that can hoist, lower, and horizontally move a suspended load. Such equipment includes, but is not limited to:
Employers are responsible for minimizing hazards to the extent possible and providing employees with the knowledge and resources to work safely in and around mobile cranes.
Determine ground conditions
Employers must determine whether the ground is sufficient to support the anticipated weight of hoisting equipment and associated loads.
The term “ground conditions” means the ability of the ground to support the equipment (including slope, compaction, and firmness).
Assess hazards
Employers must assess hazards within the work zone that would affect the safe operation of hoisting equipment, such as those of power lines and objects or personnel that would be within the work zone or swing radius of the hoisting equipment.
Ensure equipment is safe
Employers must ensure that the equipment is in safe operating condition by performing required inspections.
Train employees
Employers must train employees in the work zone to recognize hazards associated with the use of the equipment and any related duties that they are assigned to perform.
The employer must ensure that each operator is trained, certified/licensed, and evaluated before operating any equipment covered under 29 CFR 1926 Subpart CC.
Operator qualification requirements
Being certified doesn’t necessarily make an operator qualified. The most important way to determine an operator’s qualifications is through evaluation during the certification process. The Occupational Safety & Health Association (OSHA) has determined that an employer evaluation is necessary to determine the qualifications of an operator.
Just as a driver’s license doesn’t qualify an employee to operate all types of vehicles, certification doesn’t mean that an operator can use all types of cranes. Ultimately, there are two major issues associated with certified operators who switch to new equipment or tasks without evaluation:
Operator certification requirements
Before the evaluation process begins, operators must be trained and certified in operating either a specific crane type or a crane type with a specific rated capacity. Although employers are required to provide each operator-in-training with sufficient training, certification can be acquired through:
Third-party certification is portable. If an employee acquired certification from a previous employer, that certification is acceptable. However, employers are still required to evaluate an operator with certification, whether from a third party or not.
Until employees pass evaluation, they must be considered operators-in-training and must not use equipment without supervision.
Evaluation of operator qualification
The evaluation process should be performance-oriented. For operators to learn successfully and safely, a competency evaluation is critical. The requirements for the evaluation process have important advantages:
(Note: Employers are not required to comply with the evaluation process if operators are using derricks, side-booms, and cranes with a capacity of 2,000 pounds or less.)
Many incidents occur because an operator doesn’t have the equipment-specific knowledge to safely operate a crane. For this reason, OSHA has determined that accidents can be reduced if employers evaluate the operators’ skills and knowledge, as well as their ability to recognize and avert risk necessary to operate the equipment. Employees’ capabilities with the following should be evaluated:
The evaluation can be done by a qualified operator who has already passed evaluation or by an agent. If the employer decides to use an agent, the requirements for evaluation still apply and should be enforced.
An operator who successfully passes evaluation can operate equipment without supervision unless doing so would require different skills, knowledge, or ability to reduce risk. There may be many times when operators switch to new tasks or equipment. In those cases, a new evaluation should be performed to reduce the risk of injury to the operator or employees around the crane and equipment.
Employers should document each evaluation, providing:
Keep the documentation available on the worksite for the duration of the operator’s employment.
(Note: If an operator was hired prior to December 10, 2018, employers are allowed to rely on previous documentation and evaluations rather than conducting new ones.)
If there is an indication that an operator may need retraining, then the employer must provide retraining based on the topic(s) in question. Sometimes, an operator might forget information needed to safely operate equipment, and an accident could occur.
Of course, retraining won’t always happen because of an accident. If an operator indicates a lack of clarity about something, retraining is required. Retraining is ongoing. After the initial evaluation, operator retraining should be required as needed.
Validation of operator certification
As mentioned above, operators can be certified through a crane operator testing organization. These certifications are issued only after the operator has demonstrated through written and practical tests the knowledge and skills required to operate a crane.
In some cases, employers may hire an operator whose certification was acquired through a nationally accredited organization that no longer exists. In these cases, how can an employer ensure sure their operators are adequately certified?
It’s actually an easy question to answer, and options for solving the problem are available.
If an operator’s certification may not really have been issued by a nationally accredited organization, the best way to proceed is to do some digging and find information on the organization. Just because the organization no longer exists doesn’t mean information on its credibility or history isn’t available.
All findings should be clearly documented. Having information ready for immediate evaluation can prove useful should an OSHA inspection occur.
The typical construction crane can weigh many tons. Putting this weight on the ground at a construction site can lead to all sorts of problems. The most serious could be crane tip-over caused by the ground underneath the crane giving way.
The Occupational Safety & Health Association (OSHA) has determined that failure to have adequate ground conditions is a significant crane safety problem.
The term “ground conditions” is defined as the ability of the ground to support the equipment. Three key factors are involved in ground conditions:
Adequate ground conditions are essential for safe operations because the crane’s capacity and stability depend on those conditions being present. There are two key problems regarding ground conditions:
Stability and support
The requirements for ensuring adequate ground support apply both when assembling a crane and during actual crane operation.
The three ground support requirements are:
The responsibility for determining if the ground conditions are safe falls to the job’s controlling entity (CE). The CE is defined as an employer who is a prime contractor, general contractor, construction manager, or any other legal entity that has the overall responsibility for the project’s planning, quality, and completion.
Before any equipment is brought to the jobsite, the CE must possess and examine information (such as site drawings, as-built drawings, and soil analyses) to see if there are hazards beneath the crane setup area. If there are hazards identified in those documents, or if the CE has identified other hazards, then the CE must inform the crane user and operator of the hazards.
If the CE is not familiar with the crane or with the ground conditions at a particular jobsite, then the CE is responsible for having someone who is familiar with those requirements:
If there is no CE for the project, the ground support requirements in 1–3 above must be met by the employer who has authority at the site to make or arrange for ground preparations.
Assembly and disassembly
Before beginning assembly/disassembly (A/D), the A/D director has to determine whether ground conditions are adequate to support the equipment during that activity. If the A/D director or the operator determines that ground conditions do not meet the ground support requirements, that person’s employer must have a discussion with the CE regarding the ground preparations that are needed so that, with the use of suitable supporting materials/devices (if necessary), the ground support requirements can be met.
All power lines should be considered to be energized unless the utility owner/operator confirms the line has been, and continues to be, de-energized and visibly grounded at the jobsite. In addition, power lines should be presumed to be uninsulated unless the utility owner/operator or a registered professional engineer — who is a qualified person with respect to electrical power transmission and distribution — confirms that a line is insulated.
The Occupational Safety & Health Association’s (OSHA) 29 CFR 1926 Subpart CC requires employers to use a very specific and systematic approach to deal with the hazards of power lines.
(Note: Some of these requirements do not apply to work covered by Subpart V — Power Transmission and Distribution.)
When working near all voltages, the basic procedure is:
The employer is allowed to choose from several minimum clearance distance options.
In addition to frequent and periodic inspections, employers are required to inspect and test equipment to ensure it is capable of safe and reliable operation when initially set up or placed in service and after any major repairs or design modification.
The first step is to determine if power lines pose a hazard. To do this requires the work zone to be identified in one of the following ways:
Once the work zone is identified, it must be determined if any part of the crane, load line, or load (including the rigging and lifting accessories) could get closer than the trigger distance to a power line.
The trigger distance is as follows:
This determination should be made with the assumption that the crane will be operated up to its maximum working radius in the work zone.
If the crane will not get closer than the trigger distance to the power line, then the employer is not required to take any further action.
However, the employer may encounter a situation where it is necessary to increase the size of the work zone. This may occur as a result of an unanticipated need to change the crane’s position or have it operate beyond the original work zone boundaries. If that is the case, the employer must reidentify the work zone and conduct a new trigger distance assessment.
Operations below power lines
No part of the equipment, load line, or load (including rigging and lifting accessories) is allowed below a power line unless the employer has confirmed that the utility owner/operator has de-energized and (at the jobsite) visibly grounded the power line. Exceptions are listed in paragraph 1926.1408(d)(2).
If the crane could get closer than 20 feet to a power line, one of the three following options must be chosen.
Option 1 — De-energize and ground
Confirmation is received from the utility owner/operator that the power line has been de-energized and visibly grounded at the jobsite. This option is the safest and minimizes the possibility the crane would become energized if it did contact the line. If this option is chosen, the employer does not have to implement any of the other encroachment- or electrocution-prevention measures.
However, there are drawbacks to this. One is the time lag due to the amount of time needed to arrange for the utility owner to de-energize and ground the lines. Another is that when the construction project is small, the cost to de-energize and ground the lines can be excessive in comparison to the cost of the job.
Option 2 — Maintain 20-foot clearance
This option requires a minimum 20-foot clearance be maintained at all times. (If the work requires a closer approach than 20 feet, then Option 3 must be used.) The advantage of using this option is that employers don’t have to determine the exact voltage of the power lines; they only have to determine it is not more than 350kV.
To help make sure the 20-foot distance is not breached, the following precautions are required:
Option 3 — Follow Table A clearance
For this option, the employer must determine the power line’s voltage (by getting the voltage from the utility owner/operator), then determine whether any part of the crane, load line, or load (including the rigging and lifting accessories) could get closer to the power line than the minimum approach distance allowed in Table A.
When making this determination, assume the crane will be operated up to its maximum working radius when in the work zone, and comply with the minimum clearance distances in Table A. Note that, depending on the voltage, minimum clearance distances can be closer than the 20-foot clearance required for Option 1.
Table A — Minimum clearance distances | |
---|---|
Voltage (nominal, kV, alternating current) | Minimum clearance distance (feet) |
up to 50 | 10 |
over 50 to 200 | 15 |
over 200 to 350 | 20 |
over 350 to 500 | 25 |
over 500 to 750 | 35 |
over 750 to 1,000 | 45 |
over 1,000 | As established by the utility owner/operator or a registered professional engineer who is a qualified person with respect to electrical power transmission and distribution. |
The utility owner/operator must provide the requested voltage information within two days of the request.
If the crane could get closer to the power line than the minimum approach distance allowed in Table A, the same precautions mentioned in Option 2 apply.
There are requirements in place to protect employees from contact with power lines. The requirements consist of prerequisites and criteria that apply when work must be done closer than the minimum clearance distance specified in Table A of 1926.1408.
Working closer than the minimum approach distance allowed in Table A is highly discouraged.
However, there is an exception if the following three requirements are met:
The next step is to have a planning meeting that includes the employer and utility owner/operator to determine the procedures that will be followed to prevent electrical contact and electrocution. At a minimum, there are 12 procedures that must be included, per 1926.1410(d)(1) through (d)(12), and these procedures must be documented and immediately available on-site.
Traveling under or near power lines with no load
Equipment traveling under or near power lines with no load is covered at 1926.1411. The minimum clearance distances in Table T must be maintained. For traveling in poor visibility, a dedicated spotter should be used if needed, along with additional precautions.
When cranes are operating near overhead power lines, the crane, load line, or load could come into contact with the lines. If that happens, the electric current will pass through the equipment to the ground.
Anyone touching the crane in this situation will act as a ground, and the electric current will pass through the person. Even if the person doesn’t touch the equipment, the ground near the crane will be energized and present an electrocution hazard.
The Occupational Safety & Health Association (OSHA) refers to this hazard as “touch potential.” Touch potential is the voltage between the energized object and the feet of a person in contact with the object. It is equal to the difference in voltage between the object and a point some distance away.
Note that the touch potential could be nearly the full voltage across the grounded object if that object is grounded at a point remote from the place where the person is in contact with it. For example, a crane that was grounded to the system neutral and that contacted an energized line would expose any person in contact with the crane, or its uninsulated load line, to a touch potential nearly equal to the full voltage of the power line.
People should avoid approaching or coming into contact with any equipment that is operating, or any load being moved, near power lines.
If a crane comes into contact with a power line, the current will pass through the equipment to the ground. This unintentional grounding, more commonly known as a ground fault, enables voltages to be impressed on the “grounded” object that is faulting the line. A person could be at risk of injury during a fault simply by standing near the grounding point.
The Occupational Safety & Health Association (OSHA) refers to this hazard as “step potential.” Step potential is the voltage difference between the two feet of a person standing near an energized grounded object. It is equal to the difference in voltage, given by the voltage distribution curve, between two points at different distances from the electrode.
OSHA recommends that anyone who is not directly involved in the operation being performed should keep away from areas where hazardous step or touch potentials could arise. Anyone on the ground in the vicinity of transmission structures should stay at a distance where step voltages would be insufficient to cause injury.
A common method of grounding, which the Occupational Safety & Health Association (OSHA) recommends in 1926 Subpart O — Motorized Vehicles, Mechanical Equipment, and Marine Operations for work near an electrical charge, includes:
It’s important to understand that work being performed near transmitter towers or power lines (where an electrical charge can be induced in the equipment or materials being handled) must have precautionary measures implemented to dissipate induced voltages before work is performed. Being aware of the limitations of grounding is key.
Limitations of grounding
According to the preamble to Subpart CC (page 47958 of the Federal Register dated August 9, 2010), “OSHA is aware that employees are exposed to serious electric shock hazards when they are attaching grounds in accordance with 1926.1408(f). For example, when attaching the rigging to the load or the ground to the crane, the crane and load will be energized.
“OSHA views this condition as a recognized hazard and expects employers to ensure that employees are adequately protected when they are attaching grounds. Employers who fail to properly protect their employees in this regard will, in appropriate circumstances, be subject to citation under the General Duty Clause (sec. 5(a)(1)) of the OSH Act.”
Recommended evacuation procedures
Deciding whether to remain inside the cab or evacuate after power-line contact is important, especially where there is an imminent danger of fire, explosion, or other emergency. According to OSHA, to protect crane operators against electrical shock, the following procedures are recommended:
It’s important to understand that insulating links, proximity alarms, and range control (and similar) devices all have their limitations.
Insulating links
Insulating links serve a dual purpose. They protect a rigger who is handling the load if the equipment upstream of the link makes electrical contact with a power line. They also protect employees who are upstream of the insulating link if the load makes electrical contact with a power line.
The workers who are at the greatest risk of electrocution — the riggers who handle the load — are also protected by the requirement for nonconductive tag lines.
The insulating link option that is available under 1926.1408(b)(4)(v) would not protect against encroachment (certainly a limitation), but it would provide protection to employees handling the load in the event that encroachment did occur.
Insulating links must be installed between the end of the load line and the load. When so installed, these prevent the load from becoming energized in the event the load line or other part of the equipment makes electrical contact with a power line.
Preventing the load from becoming energized helps protect riggers, who often guide crane loads manually and who are at a high risk of being electrocuted if a load becomes energized. For more information on insulating links, including the phase-in period for these devices, see 1926.1408(b)(4).
Proximity alarms
A proximity alarm is a device that warns of the equipment coming near a power line. The device must be listed, labeled, or accepted by an Occupational Safety & Health Association (OSHA) Nationally Recognized Testing Laboratory. The limitations of a proximity alarm include not being operational, or effective against electrocution, during certain phases of the assembly or disassembly process of certain types of cranes.
Range control devices
A range control warning device is a device that can be set by an equipment operator to warn that the boom or jib tip is at a certain plane or multiple planes. The device must be set to alert the operator in time to prevent the boom, load line, or load (whichever is closest to the power line) from breaching the trigger distance.
As a practical matter, the device has to be set to sound the warning before the trigger distance is reached, since the operator will need some time to react and to account for the momentum of the equipment, load line, and load.
Some mobile crane accidents happen because of improper assembly and disassembly of the crane on the jobsite. Most of these accidents could be avoided by following the crane manufacturer’s requirements for assembly/disassembly (A/D). That’s why the Occupational Safety & Health Association (OSHA) requires the employer to comply with all manufacturer prohibitions applicable to assembly and disassembly, and use either:
Manufacturer procedures are generally the first choice. Employer procedures may be used only where the employer can demonstrate that the procedures used do the following:
Employer procedures must be developed by a qualified person.
Synthetic slings are an exception. Employer procedures can’t be used during rigging if the employer uses synthetic slings. Rather, the synthetic sling manufacturer’s instructions, limitations, specifications, and recommendations must be followed.
Proper assembly procedures
Accidents during A/D are often caused by:
The details of these tasks, and the location of danger areas that workers need to keep out of, often vary from one machine to another. The A/D director is responsible for making sure that the crew members know this essential information before starting the A/D process.
Crew instructions
Before beginning A/D operations, the A/D director must make sure that the crew members understand:
Before a crew member takes on a different task, or when adding new personnel during the A/D operations, the crew instruction requirements listed above must be met. Crew instructions must be given first.
Capacity limits
Rated capacity limits must not be exceeded for loads imposed on the equipment, equipment components (including rigging), lifting lugs, and equipment accessories. This prohibition applies during all phases of A/D.
In some cases, the crane being assembled is used to install its own counterweights (which can create a capacity limit risk). Early in this process, when few counterweights are in place, the crane’s capacity will be so limited that swinging beyond a certain point, or booming out beyond a certain point, may cause it to overturn.
Note that where an assist crane is being used during the A/D of another crane/derrick, the requirements for rated capacity during operations must be met.
Proper blocking plays an important role in assembly/disassembly (A/D) safety. Blocking is used in a variety of circumstances to compensate for minor ground sloping and to enhance stability by spreading out the area over which forces from the load are transferred to the ground. It is used to help support assembled equipment (usually placed under outrigger pads) and during A/D to support components.
Blocking that is undersized, insufficient in type or number, in poor condition, and/or stacked in an unstable manner could lead to a failure of support and unplanned movement or collapse of the equipment or component.
The Occupational Safety & Health Association (OSHA) defines “blocking” (also referred to as “cribbing”) as “wood or other material used to support equipment or a component and distribute loads to the ground…typically used to support latticed boom sections during assembly/disassembly and under outrigger floats.” (1926.1401)
When blocking is used to support lattice booms or lattice components, the failure to place it in the correct location could have several dangerous consequences. For example, incorrect placement could cause part of the lattice boom/component to bear too much force and damage it.
Damage to the boom/component could compromise structural integrity and, in some cases, may not be immediately noticed. If the assembly process were to continue, the boom/component could fail.
Improper blocking location may also result in a failure to provide adequate support of the boom/component. One example is blocking used to provide support to a boom section, such as after pins are removed. If the blocking is in the wrong place, once the pins are removed, unplanned movement or collapse could result.
OSHA’s regulatory requirement is stated simply as, “The size, amount, condition and method of stacking the blocking must be sufficient to sustain the loads and maintain stability.” (1926.1404)
An assist crane is a crane used to assist in assembling or disassembling a crane. When using an assist crane, the loads that will be imposed on the assist crane at each phase of assembly/disassembly (A/D) must be verified (before A/D begins) with at least one of the following methods:
At times, resulting loads on assist cranes during the A/D process are not properly anticipated. For example, when a boom is being disassembled in a cantilevered position, an assist crane is sometimes used to help support the boom. In some instances, the load is within the assist crane’s rated capacity prior to pin removal but exceeds its rated capacity once the pins are removed, causing a collapse.
The point(s) of attachment of rigging to a boom (or boom sections, or jib or jib sections) must be suitable for preventing structural damage and allowing safe handling of these components. Damage could compromise structural integrity and, in some cases, may not be immediately noticed. If that component is used, the boom/component could fail.
Safe handling of the boom/jib or boom/jib sections requires using pick points that will result in the boom/section being at the intended angle (90 degrees to the load line or some other intended angle) when hoisted.
For example, if the boom/section is intended to be horizontal, and only one pick point is going to be used, the pick point must coincide with the center of gravity. If the boom/section is intended to be at some other angle, a pick point would need to be identified that would generate that angle. Failing to do this could cause unintended movement during connecting or disconnecting the boom/section.
Often the method used for maintaining stability during assembly/disassembly (A/D) depends on supporting or rigging a component (or set of components) so that it remains balanced throughout the lift. In such instances, the A/D director is required to identify the center of gravity of the load.
One example of a situation where it would be necessary to identify the center of gravity is if the A/D crew is relying on an assist crane to suspend a component in a horizontal position. In this case, the center of gravity must be identified in order to correctly install the rigging.
If the center of gravity is not identified before installing the rigging, employees might try to compensate by riding on the section/component while it is being moved into place, which is quite dangerous. Also, in such a situation, if the component gets “hung up,” it can move unexpectedly when freed.
Some methods for maintaining stability do not depend on rigging or supporting the component to attain horizontal balance. For example, if two adjoining sections of a boom are being disconnected from each other, and both sections are supported at all four end points by blocking, then identifying the center of gravity may not be necessary.
There may be instances where the A/D method being used requires the identification of the center of gravity, but the employer can’t get sufficient information to make that identification. If the center of gravity cannot be identified, precautions must be taken to prevent unintended dangerous movement.
The boom sections, boom suspension systems (such as gantry A-frames and jib struts), and components must be rigged or supported to maintain stability upon the removal of the pins.
The Occupational Safety & Health Association (OSHA) defines “boom suspension systems” as “a system of pendants, running ropes, sheaves, and other hardware which supports the boom tip and controls the boom angle.” (1926.1401)
The process of pin removal is particularly hazardous. Potential energy in these sections, systems, and components can be released suddenly during pin removal, resulting in unanticipated movement ranging from shifting to collapse. Even small movements can result in injury, including amputations; larger movements and collapses can cause fatal injuries.
The key to preventing these injuries and fatalities is ensuring that the sections/components remain stable upon the removal of the pins. Instability can have a variety of causes, including improper A/D sequencing, improper rigging, incorrectly designed support, blocking failures, and ground compression.
The assembly/disassembly (A/D) director supervising the A/D operation must address known hazards associated with the operation and come up with methods to protect the employees from those hazards. The A/D director must consider each hazard, determine the appropriate means of addressing it, and oversee the implementation of that method.
Snagging
Suspension ropes and pendants must not be allowed to catch on the boom or jib connection pins or cotter pins (including keepers and locking pins). This could damage the cables or other components and result in injury.
Pendant cables are typically used in a latticed boom crane system to easily change the length of the boom suspension system without completely changing the rope on the drum when the boom length is increased or decreased. In many cases, the pendant cables hang alongside the boom and may get caught (snagged) on the pins, bolts, or keepers as the operator raises the boom.
If snagging occurs, the cables can be damaged, or the boom may rise then drop suddenly as a snagged cable releases from the pin. This can result in shock loading and damage to cables and components.
Counterweight strikes
Counterweights are usually large, heavy plates made of steel and/or concrete. The A/D process typically involves the installation and removal of counterweights.
During the installation/removal process, employees tend to be in close proximity to counterweights. If a counterweight sways as it’s being installed or removed, an employee can be struck by it or crushed between it and the crane.
The A/D director must address this aspect of the hazard, such as by taking steps to have the operator minimize the amount of sway and by positioning the employees to minimize their hazard exposure.
Additionally, after the counterweights are installed, the crane may have to swing to complete the boom assembly. The A/D director is required to address this aspect of the hazard as well, such as through the proper positioning of employees and enhancing their awareness of the counterweight swing zone so that they will avoid being struck or crushed.
Loss of backward stability
There are three points during the A/D process at which there is a heightened risk of loss of backward stability. These are:
Therefore, before any of these occur, the A/D director is required to consider whether precautions need to be instituted to ensure that backward stability is maintained.
One common hazard is an operator swinging or moving the crane when assembly/disassembly (A/D) personnel are in a crush/caught-in-between zone and out of the operator’s view. An effective and practical means of preventing these accidents is through a communication procedure that provides key information to, and coordination between, the operator and these workers.
That’s why the operator must be informed when a crew member is going to a location in, on, under, or near the equipment or load that is out of view of the operator, and where the movement of the equipment could injure the worker.
When the operator knows that a crew member went to a hazardous location, the operator must not move any part of the equipment (or load) until the operator is informed via a prearranged system of communication that the crew member is in a safe position.
An example of such a system would be the use of a signal person who gives an all-clear signal to the operator once the signal person sees that the employee has exited the hazard area.
Another example would be where the employee in the hazard area is equipped with a portable air horn and, in accordance with a prearranged horn signal system, sounds an appropriate signal to the operator that the employee has exited the hazard area. To be effective, the prearranged signal system needs to be designed so that this all-clear signal could not be confused with a horn signal from some other employee for another purpose.
Boom hoist brake failure is a hazard that can be present during both assembly and disassembly, although it is more typically an assembly hazard. In many older cranes, the boom hoist brake mechanism has an external or internal mechanical brake band that operates by pressing against the hoist drum. As the configuration of the crane changes and, for example, more boom is added, this type of boom hoist brake may slip unless it has been adjusted to hold the extra weight.
The inability of an unadjusted brake to hold the increased load will not be evident until the additional boom section has been added and the operator attempts to rely on the brake in a subsequent phase of the operation. If the operator does not first raise the boom a small amount after the section has been added (with the crew clear of the boom) to test the brake, employees could be injured later in the process when the operator manipulates the boom and is unexpectedly unable to brake it.
In many cases, if the brake is insufficient, an adjustment to it will correct the problem. If it remains insufficient, the employer is required to use a boom hoist pawl, other locking device, backup braking device, or another method of preventing dangerous boom movement (such as blocking or using an assist crane to support the load) from a boom hoist brake failure.
The brake test needs to be performed before anyone relies on the brake. It needs to accurately account for the loads that will be placed on the brake.
The assembly/disassembly (A/D) director is required to address hazards caused by wind speed and weather to ensure that the safe A/D of the equipment is not compromised. Selecting any one particular speed as a maximum would be arbitrary because of the variety of factors involved.
For example:
The A/D director must determine the maximum safe wind speed under the circumstances.
Other weather conditions that can affect the safety of A/D include, for example, ice accumulation on crane components. Ice can both add to the weight of the components and make surfaces on which employees work slippery and dangerous. The A/D director must address weather conditions that affect the safety of the operation.
One hazard an employee may encounter is removing pins while under the boom (and jib or similar components). If the wrong pins are removed while employees are under the component, it can move or collapse.
Even when pins are removed in the correct order, there may be unexpected stresses in the component, such as stored kinetic energy, that may not be apparent until that energy is released upon the removal of the pin. This can result in unexpected movement of the component.
Removing pins while under the boom should be avoided when possible. There is an exception: where the employer demonstrates that site constraints require one or more employees to be under the boom, jib, or other components when pins (or similar devices) are being removed, the assembly/disassembly (A/D) director must implement procedures that minimize the risk of unintended dangerous movement and minimize the duration and extent of exposure under the boom.
Sample scenario for the exception
In this scenario, there is a boom that cannot be disassembled on the ground because of aboveground piping (as might be found, for example, in an oil refinery) that precludes lowering the boom to the ground. The boom must therefore be disassembled in the air, and the employees who remove the pins must perform that work from an aerial lift whose base is positioned on one side (the near side) of the boom.
To gain access to the pins on the far side, the aerial lift basket must move under the boom, since, due to lack of room, the aerial lift cannot be repositioned on the far side.
To minimize the risk of unintended dangerous movement while the pins are removed, the A/D director uses an assist crane that is rigged to support the boom section that is being detached, using particular care to ensure that the section end that is near the employee(s) removing the pins is well supported.
The duration and extent of exposure is minimized by removing the far side pins first, moving the aerial lift basket as soon as possible to the near side so that the employees are no longer under the boom, and then removing the near side pins.
To minimize risks on the jobsite, employers in the construction industry using mobile cranes in the construction industry must address the following issues.
Cantilevered boom sections
A common mistake in assembly/disassembly is cantilevering too much boom. When this is done, structural failure can occur in components such as the mast/gantry, boom sections, and lifting lugs.
Employees may be struck by falling components from this type of failure. To prevent accidents from cantilevering too much boom during assembly/disassembly, the manufacturer’s limitations on cantilevering must not be exceeded.
If the manufacturer’s limitations are not available, the employer is required to have a registered professional engineer (RPE) determine the appropriate limitations, and to abide by those limitations. The RPE’s determination must be in writing to ensure that the assessment has been done.
Weight of components
As with any load to be lifted by a crane/derrick, the weight of the components must be available to the operator so that the operator can determine if the lift can be performed within the crane/derrick’s capacity. This requirement applies irrespective of whether the component is being hoisted by the crane being assembled/disassembled or by an assist crane.
Manufacturer prohibitions
Manufacturers’ prohibitions always take precedence. A prohibition specified by the manufacturer is a clear sign that if it is not heeded, a significant hazard would likely be created.
An employer would be able to choose to use either manufacturer assembly/disassembly procedures or the workplace’s own, as long as the procedures meet the requirements. However, in either case, the manufacturer prohibitions regarding assembly or disassembly would need to be met.
Shipping pins
Reusable shipping pins, straps, links, and similar equipment must be removed. Once removed, they must be stowed or otherwise stored so that they do not present a falling object hazard.
Being properly stowed might include being placed in a special hole or bracket designed to keep the item from being dislodged. Storage on the equipment could include placing them in an equipment box in the cab.
Pile driving
Equipment used in pile driving operations must not have a jib attached. The constant pounding of the pile driving hammer and the sometimes-rapid descent of the pile causes the boom to bounce.
If a jib were installed on the tip, as the boom bounces the jib could be thrown backward against its stops, which would likely cause structural damage to the boom. The damage could cause the boom to immediately fail or could diminish its capacity.
Rigging work
When rigging is used for assembly/disassembly, the employer must make sure that:
To determine the proper selection of components and proper configurations, employers should consult the manufacturer’s instructions, limitations, and specifications. Regarding component selection, hazards are associated with the use of components that the manufacturer neither intended nor planned for incorporation into the equipment. Such components could adversely affect the capacity and performance of the crane/derrick, make the manufacturer’s specifications (including the load chart) and instructions inapplicable, and adversely affect other components on the crane/derrick.
Similar hazards are posed by configuring the crane/derrick in a manner that does not accord with the manufacturer’s instructions, limitations, and specifications. This could occur when trucks carrying boom sections arrive out of sequence.
To save time, some employers assemble the sections in the order in which they arrive rather than waiting for the correct section. This results in a crane/derrick configured differently than intended by the manufacturer. Because the crane/derrick is designed and tested as a unit, the failure to configure the crane/derrick as the manufacturer had intended could present the same hazards as those described above for improper component selection.
There may be instances when the crane manufacturer no longer exists and the employer can no longer obtain the manufacturer’s instructions, limitations, and specifications regarding the selection of components and configuration of the equipment. In such cases, a registered professional engineer familiar with the type of equipment involved must approve, in writing, the component selection and configuration.
Section 1926.1434 allows cranes/derricks to be modified under certain circumstances. To the extent a crane/derrick is modified in accordance with this section, the employer cannot be required to follow the manufacturer’s original instructions, limitations, and specifications regarding component selection and configuration regarding those modifications. Instead, the employer is required to follow the component selection and configuration requirements approved according to 1926.1434.
Finally, the equipment must be inspected after assembly has been completed to ensure that the component selection and configuration are correct.
Outriggers are designed to take all load off the tires. Stabilizers are designed to relieve some, but not all, of the sprung weight for the purpose of increasing the stability of the vehicle.
Any time outriggers or stabilizers are used, all of the following requirements must be met (except as otherwise indicated):
The work area is the accessible areas in which the equipment’s rotating superstructure (whether permanently or temporarily mounted) poses a reasonably foreseeable risk of:
Hazards of rotating superstructures
The rotation of a crane’s superstructure can cause serious injury and death to employees working near the crane. Specifically, there are two hazards employees need to be aware of:
The employer is required to erect and maintain control lines, warning lines, railings, or similar barriers to mark the boundaries of the hazard areas. One type of barrier that is often used is attached directly to the crane and moves with the equipment.
There is an exception, and that is when the employer can demonstrate that it is feasible to erect such barriers on neither the ground nor the equipment. In that case, the hazard areas must be clearly marked by a combination of warning signs (such as “Danger — Swing/Crush Zone”) and high-visibility markings on the equipment that identify the hazard areas. In addition, the employer must train each employee to understand what these markings signify.
Cranes working near each other
If there are several cranes working near each other, and if any part of a crane/derrick is within the working radius of another crane/derrick, the controlling entity (CE) must institute a system to coordinate operations. If there is no CE, the employer (if there is only one employer operating the multiple pieces of equipment) or employers must devise and institute such a system.
There may be times when an employee must go into part of the crane’s swing hazard area that is out of sight of the crane operator. Before doing so, the crane operator must be informed that someone is entering the swing hazard area.
Once the crane operator has been informed that an employee is within the swing hazard area, the operator must not rotate the superstructure until the operator is informed, according to a pre-arranged system of communication, that the employee is in a safe position.
An example of such a communication system would be the use of a signal person who gives an all-clear signal to the operator once the signal person sees that the employee has exited the hazard area. Another example would be where the employee in the hazard area is equipped with a portable air horn and, in accordance with a pre-arranged horn signal system, sounds an appropriate signal to the operator that the employee has exited the hazard area.
To be effective, the pre-arranged signal system needs to be designed so that this all-clear signal could not be confused with a horn signal from some other employee for another purpose.
The Occupational Safety & Health Association’s (OSHA) 29 CFR 1926 Subpart CC has specific requirements for keeping employees clear of the load:
OSHA defines “fall zone” as the area (including but not limited to the area directly beneath the load) in which it is reasonably foreseeable that partially or completely suspended materials could fall in the event of an accident. For example, if wind is causing the load to swing, the employer would need to consider the breadth of the swinging (or potential swinging) in determining the extent of the fall zone.
Another example is where a bundle of materials is suspended and some loose materials at the top of the bundle may slide off sideways. In such a case, those materials could foreseeably fall outside the area directly beneath the load.
When employees are engaged in hooking, unhooking, or guiding the load, or in the initial connection of a load to a component or structure, and are within the fall zone, all of the following criteria must be met:
When a load is being landed, only employees needed to receive a load are permitted to be within the fall zone. An employee receiving a load will typically need to be within the fall zone when the load is being landed because that is the time when the load needs to be guided to a specific landing point.
In tilt-up and tilt-down operations, one end of a component, such as a precast panel, is either:
Note: These requirements do not apply when receiving a load; they only apply during tilt-up and tilt-down operations.
During a tilt-up or tilt-down operation:
An employee is considered “essential to the operation” if the employee is conducting one of the following operations and the employer can demonstrate that it’s infeasible to perform that operation from outside the fall zone:
The requirements for signs, signals, and markings in the Occupational Safety & Health Association’s (OSHA) 29 CFR 1926 Subpart CC include the following.
Leaving the equipment unattended — Barricades/Caution lines and notices
When the equipment is left unattended, barricades or caution lines and notices must be erected to prevent all employees from entering the fall zone. No employees are permitted in the fall zone when the equipment is unattended, including those who are:
Out of service — Tag-out
When the employer has taken the equipment out of service, a tag must be placed in the cab stating that the equipment is out of service and is not to be used. When the employer has taken a crane function(s) out of service, a tag must be placed in a conspicuous position stating that the function is out of service and is not to be used.
If there is a warning (tag-out or maintenance/do not operate) sign on:
then the operator must not activate the switch or start the equipment until the sign has been removed by a person authorized to remove it, or until the operator has verified that:
A study of crane-related fatalities in the U.S. construction industry found that 2 percent of the fatalities resulted from falls. Falls from cranes, particularly when the operator is entering or leaving the crane, also cause numerous non-fatal injuries to construction workers.
Training
Employers must train each employee who may be exposed to fall hazards while on, or hoisted by, equipment covered by the Occupational Safety & Health Association’s (OSHA) 29 CFR 1926 Subpart CC. The training must consist of:
Types of fall protection
“Fall protection equipment” is defined as “guardrail systems, safety net systems, personal fall arrest systems, positioning device systems, or fall restraint systems.” (1926.760)
“Fall restraint system” is defined as “a fall protection system that prevents the user from falling any distance. The system is comprised of either a body belt or body harness, along with an anchorage, connectors and other necessary equipment. The other components typically include a lanyard and may also include a lifeline and other devices.” (1926.751)
The types of fall protection required for cranes are the same fall protection equipment required under other OSHA standards.
Personal fall arrest equipment and use
Personal fall arrest system components must be used in personal fall arrest and fall restraint systems and must conform to the criteria in 1926.502(d), except that 1926.502(d)(15) does not apply to components used in personal fall arrest and fall restraint systems. Either body belts or body harnesses must be used in personal fall arrest and fall restraint systems.
There is a required use exception, namely that operators do not need to be tied off when moving to and from their crane cabs.
Fall protection is also not required for employees on decks, since that equipment is typically designed so that employees are not exposed to a fall hazard.
The following information is for crane manufacturers and for employers. Employees should also be aware of these requirements.
Existing equipment manufactured before November 8, 2011, does not have to be retrofitted with new steps, handholds, and railings simply because the existing design may vary from what is required in Subpart CC.
For non-assembly/disassembly work, employees must use provided fall protection equipment when they are on a walking/working surface with an unprotected side or edge more than 6 feet above a lower level when moving point-to-point (when the employee is in the process of going to or from a workstation).
The following table describes point-to-point movements requiring fall protection.
On non-lattice booms (whether horizontal or not horizontal) | Non-lattice booms generally present more hazards (than lattice booms) to workers who must walk them to reach other work areas, devices, and equipment. Non-lattice booms are typically extensible booms, and the surface is usually oily from the hydraulic mechanisms. |
On lattice booms that are not horizontal | An employee may need to move point-to-point on a lattice boom to inspect a part that may need repair, or to make the repair. In many cases, the boom may not be horizontal, since space limitations can make it difficult to lower the boom to perform the work. Since the boom would be elevated, there would usually be a point on the boom above the level of the worker’s feet to attach a lanyard. |
On horizontal lattice booms where the fall distance is 15 feet or more | The 15-foot minimum distance is used because a personal fall arrest system tied off at the level of the employee’s feet, with a lanyard long enough to allow the employee the range of movement necessary for this work, might not prevent the employee from falling to the next lower level. |
Employees must also use fall protection equipment when they are on a walking/working surface with an unprotected side or edge more than 6 feet above a lower level and not moving point-to-point. For example, if an employee is stationary at a workstation on any part of the equipment (including the boom, of any type), the employee needs fall protection, except when the employee is:
Assembly/Disassembly work
For assembly/disassembly (A/D) work, employees must use provided fall protection equipment when they are on a walking/working surface with an unprotected side or edge more than 15 feet above a lower level, except when the employee is
The Occupational Safety & Health Association (OSHA) has a new enforcement policy that excludes monorail hoists from the requirements of Subpart CC — Cranes and Derricks in Construction, as long as employers meet other OSHA requirements.
The following is from an OSHA Memorandum issued June 30, 2017.
“The scope of Cranes and Derricks in Construction (the cranes standard, 29 CFR Part 1926, subpart CC) includes a functional definition for the equipment covered. The standard applies to ‘power-operated equipment, when used in construction, that can hoist, lower, and horizontally move a suspended load.’ (29 CFR 1926.1400[a]). Monorail hoists are not explicitly excluded from the scope of the rule, and OSHA has issued several letters of interpretation confirming the crane standard’s coverage of specific monorail hoists in certain construction operations.
“As a number of stakeholders have pointed out, the standard is not a perfect fit for monorail hoists, and OSHA intends to consider rulemaking options to address this issue. The purpose of this memorandum is to announce a temporary enforcement policy pending the resolution of that rulemaking process.
“Most monorail hoist systems have a completely fixed monorail (I-beam). When used in construction, these hoisting systems are typically mounted on equipment such as work vehicles, trailers, and scaffolding systems. The monorails can be extended and contracted in only a fixed horizontal direction to hoist materials and can only hoist them as high as the monorail. Some examples of materials commonly lifted and placed by monorail hoists during construction are precast concrete components (septic tanks, storm drain and sewer conduits, vaults, etc.); storage tanks (propane, oil, etc.); mechanical components (engines, commercial generators, etc.); trade specific components (electrical transformers, industrial spooled materials, sewer lids, etc.); and temporary storage units.
“Monorail hoists present unique issues. Many monorail hoist manufacturers do not design their systems to meet any particular criteria recommended in consensus standards, though the designs of their hoisting mechanisms most resemble those of overhead hoists covered by ASME 830.172015 (Cranes and Monorails (With Underhung Trolley or Bridge)).
“Stakeholders have pointed out that a number of the provisions of the crane standard add very little protection when these monorail hoists are used. For example, the stakeholders have told OSHA that because these monorails are fixed such that they do not angle up or down, the equipment does not warrant the elevated level of protections from power-line contact required by the crane standard. They also note that monorails cannot boom out significantly beyond the wheelbase of a vehicle or the base of its supporting structure, and thus the hoisting equipment does not pose the dangerous cantilevering and stability hazards that are addressed by requirements of the crane standard.
“Furthermore, they assert that there is no need for specific protections from hazards posed by booming out loads, boom free fall, equipment swing radius, or any crane-related hazards that would necessitate the use of devices like level indicators, boom/jib stops, boom/jib limiting devices, boom length/radius indicators, and drum hoist rotation indicators.
“Finally, stakeholders have pointed out that the loads handled by monorail hoists are not heavy enough to trigger the need for a load weighing device or the use of load charts to prevent overloading and tipping the hosting equipment.
“However, it is clear that monorail and overhead hoist systems present recognized workplace hazards, including those addressed by 29 CFR 1926.554 (Overhead hoists), ASME B30. l 7, and various manufacturers’ recommendations. For the reasons discussed above, and until the application of the cranes standard to monorail hoists is revisited through rulemaking, OSHA intends to exercise its enforcement discretion by not citing employers for failing to achieve full compliance with the cranes standard when monorail hoists are used, if the following conditions are met to protect employees:
“Should an employer operating such equipment fail to comply fully with all of the requirements described, the requirements of the crane standard would apply.”
Employers are responsible for minimizing hazards to the extent possible and providing employees with the knowledge and resources to work safely in and around mobile cranes.
Determine ground conditions
Employers must determine whether the ground is sufficient to support the anticipated weight of hoisting equipment and associated loads.
The term “ground conditions” means the ability of the ground to support the equipment (including slope, compaction, and firmness).
Assess hazards
Employers must assess hazards within the work zone that would affect the safe operation of hoisting equipment, such as those of power lines and objects or personnel that would be within the work zone or swing radius of the hoisting equipment.
Ensure equipment is safe
Employers must ensure that the equipment is in safe operating condition by performing required inspections.
Train employees
Employers must train employees in the work zone to recognize hazards associated with the use of the equipment and any related duties that they are assigned to perform.
The employer must ensure that each operator is trained, certified/licensed, and evaluated before operating any equipment covered under 29 CFR 1926 Subpart CC.
Operator qualification requirements
Being certified doesn’t necessarily make an operator qualified. The most important way to determine an operator’s qualifications is through evaluation during the certification process. The Occupational Safety & Health Association (OSHA) has determined that an employer evaluation is necessary to determine the qualifications of an operator.
Just as a driver’s license doesn’t qualify an employee to operate all types of vehicles, certification doesn’t mean that an operator can use all types of cranes. Ultimately, there are two major issues associated with certified operators who switch to new equipment or tasks without evaluation:
Operator certification requirements
Before the evaluation process begins, operators must be trained and certified in operating either a specific crane type or a crane type with a specific rated capacity. Although employers are required to provide each operator-in-training with sufficient training, certification can be acquired through:
Third-party certification is portable. If an employee acquired certification from a previous employer, that certification is acceptable. However, employers are still required to evaluate an operator with certification, whether from a third party or not.
Until employees pass evaluation, they must be considered operators-in-training and must not use equipment without supervision.
Evaluation of operator qualification
The evaluation process should be performance-oriented. For operators to learn successfully and safely, a competency evaluation is critical. The requirements for the evaluation process have important advantages:
(Note: Employers are not required to comply with the evaluation process if operators are using derricks, side-booms, and cranes with a capacity of 2,000 pounds or less.)
Many incidents occur because an operator doesn’t have the equipment-specific knowledge to safely operate a crane. For this reason, OSHA has determined that accidents can be reduced if employers evaluate the operators’ skills and knowledge, as well as their ability to recognize and avert risk necessary to operate the equipment. Employees’ capabilities with the following should be evaluated:
The evaluation can be done by a qualified operator who has already passed evaluation or by an agent. If the employer decides to use an agent, the requirements for evaluation still apply and should be enforced.
An operator who successfully passes evaluation can operate equipment without supervision unless doing so would require different skills, knowledge, or ability to reduce risk. There may be many times when operators switch to new tasks or equipment. In those cases, a new evaluation should be performed to reduce the risk of injury to the operator or employees around the crane and equipment.
Employers should document each evaluation, providing:
Keep the documentation available on the worksite for the duration of the operator’s employment.
(Note: If an operator was hired prior to December 10, 2018, employers are allowed to rely on previous documentation and evaluations rather than conducting new ones.)
If there is an indication that an operator may need retraining, then the employer must provide retraining based on the topic(s) in question. Sometimes, an operator might forget information needed to safely operate equipment, and an accident could occur.
Of course, retraining won’t always happen because of an accident. If an operator indicates a lack of clarity about something, retraining is required. Retraining is ongoing. After the initial evaluation, operator retraining should be required as needed.
Validation of operator certification
As mentioned above, operators can be certified through a crane operator testing organization. These certifications are issued only after the operator has demonstrated through written and practical tests the knowledge and skills required to operate a crane.
In some cases, employers may hire an operator whose certification was acquired through a nationally accredited organization that no longer exists. In these cases, how can an employer ensure sure their operators are adequately certified?
It’s actually an easy question to answer, and options for solving the problem are available.
If an operator’s certification may not really have been issued by a nationally accredited organization, the best way to proceed is to do some digging and find information on the organization. Just because the organization no longer exists doesn’t mean information on its credibility or history isn’t available.
All findings should be clearly documented. Having information ready for immediate evaluation can prove useful should an OSHA inspection occur.
Employers should document each evaluation, providing:
Keep the documentation available on the worksite for the duration of the operator’s employment.
(Note: If an operator was hired prior to December 10, 2018, employers are allowed to rely on previous documentation and evaluations rather than conducting new ones.)
If there is an indication that an operator may need retraining, then the employer must provide retraining based on the topic(s) in question. Sometimes, an operator might forget information needed to safely operate equipment, and an accident could occur.
Of course, retraining won’t always happen because of an accident. If an operator indicates a lack of clarity about something, retraining is required. Retraining is ongoing. After the initial evaluation, operator retraining should be required as needed.
Validation of operator certification
As mentioned above, operators can be certified through a crane operator testing organization. These certifications are issued only after the operator has demonstrated through written and practical tests the knowledge and skills required to operate a crane.
In some cases, employers may hire an operator whose certification was acquired through a nationally accredited organization that no longer exists. In these cases, how can an employer ensure sure their operators are adequately certified?
It’s actually an easy question to answer, and options for solving the problem are available.
If an operator’s certification may not really have been issued by a nationally accredited organization, the best way to proceed is to do some digging and find information on the organization. Just because the organization no longer exists doesn’t mean information on its credibility or history isn’t available.
All findings should be clearly documented. Having information ready for immediate evaluation can prove useful should an OSHA inspection occur.
The typical construction crane can weigh many tons. Putting this weight on the ground at a construction site can lead to all sorts of problems. The most serious could be crane tip-over caused by the ground underneath the crane giving way.
The Occupational Safety & Health Association (OSHA) has determined that failure to have adequate ground conditions is a significant crane safety problem.
The term “ground conditions” is defined as the ability of the ground to support the equipment. Three key factors are involved in ground conditions:
Adequate ground conditions are essential for safe operations because the crane’s capacity and stability depend on those conditions being present. There are two key problems regarding ground conditions:
Stability and support
The requirements for ensuring adequate ground support apply both when assembling a crane and during actual crane operation.
The three ground support requirements are:
The responsibility for determining if the ground conditions are safe falls to the job’s controlling entity (CE). The CE is defined as an employer who is a prime contractor, general contractor, construction manager, or any other legal entity that has the overall responsibility for the project’s planning, quality, and completion.
Before any equipment is brought to the jobsite, the CE must possess and examine information (such as site drawings, as-built drawings, and soil analyses) to see if there are hazards beneath the crane setup area. If there are hazards identified in those documents, or if the CE has identified other hazards, then the CE must inform the crane user and operator of the hazards.
If the CE is not familiar with the crane or with the ground conditions at a particular jobsite, then the CE is responsible for having someone who is familiar with those requirements:
If there is no CE for the project, the ground support requirements in 1–3 above must be met by the employer who has authority at the site to make or arrange for ground preparations.
Assembly and disassembly
Before beginning assembly/disassembly (A/D), the A/D director has to determine whether ground conditions are adequate to support the equipment during that activity. If the A/D director or the operator determines that ground conditions do not meet the ground support requirements, that person’s employer must have a discussion with the CE regarding the ground preparations that are needed so that, with the use of suitable supporting materials/devices (if necessary), the ground support requirements can be met.
All power lines should be considered to be energized unless the utility owner/operator confirms the line has been, and continues to be, de-energized and visibly grounded at the jobsite. In addition, power lines should be presumed to be uninsulated unless the utility owner/operator or a registered professional engineer — who is a qualified person with respect to electrical power transmission and distribution — confirms that a line is insulated.
The Occupational Safety & Health Association’s (OSHA) 29 CFR 1926 Subpart CC requires employers to use a very specific and systematic approach to deal with the hazards of power lines.
(Note: Some of these requirements do not apply to work covered by Subpart V — Power Transmission and Distribution.)
When working near all voltages, the basic procedure is:
The employer is allowed to choose from several minimum clearance distance options.
In addition to frequent and periodic inspections, employers are required to inspect and test equipment to ensure it is capable of safe and reliable operation when initially set up or placed in service and after any major repairs or design modification.
The first step is to determine if power lines pose a hazard. To do this requires the work zone to be identified in one of the following ways:
Once the work zone is identified, it must be determined if any part of the crane, load line, or load (including the rigging and lifting accessories) could get closer than the trigger distance to a power line.
The trigger distance is as follows:
This determination should be made with the assumption that the crane will be operated up to its maximum working radius in the work zone.
If the crane will not get closer than the trigger distance to the power line, then the employer is not required to take any further action.
However, the employer may encounter a situation where it is necessary to increase the size of the work zone. This may occur as a result of an unanticipated need to change the crane’s position or have it operate beyond the original work zone boundaries. If that is the case, the employer must reidentify the work zone and conduct a new trigger distance assessment.
Operations below power lines
No part of the equipment, load line, or load (including rigging and lifting accessories) is allowed below a power line unless the employer has confirmed that the utility owner/operator has de-energized and (at the jobsite) visibly grounded the power line. Exceptions are listed in paragraph 1926.1408(d)(2).
If the crane could get closer than 20 feet to a power line, one of the three following options must be chosen.
Option 1 — De-energize and ground
Confirmation is received from the utility owner/operator that the power line has been de-energized and visibly grounded at the jobsite. This option is the safest and minimizes the possibility the crane would become energized if it did contact the line. If this option is chosen, the employer does not have to implement any of the other encroachment- or electrocution-prevention measures.
However, there are drawbacks to this. One is the time lag due to the amount of time needed to arrange for the utility owner to de-energize and ground the lines. Another is that when the construction project is small, the cost to de-energize and ground the lines can be excessive in comparison to the cost of the job.
Option 2 — Maintain 20-foot clearance
This option requires a minimum 20-foot clearance be maintained at all times. (If the work requires a closer approach than 20 feet, then Option 3 must be used.) The advantage of using this option is that employers don’t have to determine the exact voltage of the power lines; they only have to determine it is not more than 350kV.
To help make sure the 20-foot distance is not breached, the following precautions are required:
Option 3 — Follow Table A clearance
For this option, the employer must determine the power line’s voltage (by getting the voltage from the utility owner/operator), then determine whether any part of the crane, load line, or load (including the rigging and lifting accessories) could get closer to the power line than the minimum approach distance allowed in Table A.
When making this determination, assume the crane will be operated up to its maximum working radius when in the work zone, and comply with the minimum clearance distances in Table A. Note that, depending on the voltage, minimum clearance distances can be closer than the 20-foot clearance required for Option 1.
Table A — Minimum clearance distances | |
---|---|
Voltage (nominal, kV, alternating current) | Minimum clearance distance (feet) |
up to 50 | 10 |
over 50 to 200 | 15 |
over 200 to 350 | 20 |
over 350 to 500 | 25 |
over 500 to 750 | 35 |
over 750 to 1,000 | 45 |
over 1,000 | As established by the utility owner/operator or a registered professional engineer who is a qualified person with respect to electrical power transmission and distribution. |
The utility owner/operator must provide the requested voltage information within two days of the request.
If the crane could get closer to the power line than the minimum approach distance allowed in Table A, the same precautions mentioned in Option 2 apply.
If the crane could get closer than 20 feet to a power line, one of the three following options must be chosen.
Option 1 — De-energize and ground
Confirmation is received from the utility owner/operator that the power line has been de-energized and visibly grounded at the jobsite. This option is the safest and minimizes the possibility the crane would become energized if it did contact the line. If this option is chosen, the employer does not have to implement any of the other encroachment- or electrocution-prevention measures.
However, there are drawbacks to this. One is the time lag due to the amount of time needed to arrange for the utility owner to de-energize and ground the lines. Another is that when the construction project is small, the cost to de-energize and ground the lines can be excessive in comparison to the cost of the job.
Option 2 — Maintain 20-foot clearance
This option requires a minimum 20-foot clearance be maintained at all times. (If the work requires a closer approach than 20 feet, then Option 3 must be used.) The advantage of using this option is that employers don’t have to determine the exact voltage of the power lines; they only have to determine it is not more than 350kV.
To help make sure the 20-foot distance is not breached, the following precautions are required:
Option 3 — Follow Table A clearance
For this option, the employer must determine the power line’s voltage (by getting the voltage from the utility owner/operator), then determine whether any part of the crane, load line, or load (including the rigging and lifting accessories) could get closer to the power line than the minimum approach distance allowed in Table A.
When making this determination, assume the crane will be operated up to its maximum working radius when in the work zone, and comply with the minimum clearance distances in Table A. Note that, depending on the voltage, minimum clearance distances can be closer than the 20-foot clearance required for Option 1.
Table A — Minimum clearance distances | |
---|---|
Voltage (nominal, kV, alternating current) | Minimum clearance distance (feet) |
up to 50 | 10 |
over 50 to 200 | 15 |
over 200 to 350 | 20 |
over 350 to 500 | 25 |
over 500 to 750 | 35 |
over 750 to 1,000 | 45 |
over 1,000 | As established by the utility owner/operator or a registered professional engineer who is a qualified person with respect to electrical power transmission and distribution. |
The utility owner/operator must provide the requested voltage information within two days of the request.
If the crane could get closer to the power line than the minimum approach distance allowed in Table A, the same precautions mentioned in Option 2 apply.
There are requirements in place to protect employees from contact with power lines. The requirements consist of prerequisites and criteria that apply when work must be done closer than the minimum clearance distance specified in Table A of 1926.1408.
Working closer than the minimum approach distance allowed in Table A is highly discouraged.
However, there is an exception if the following three requirements are met:
The next step is to have a planning meeting that includes the employer and utility owner/operator to determine the procedures that will be followed to prevent electrical contact and electrocution. At a minimum, there are 12 procedures that must be included, per 1926.1410(d)(1) through (d)(12), and these procedures must be documented and immediately available on-site.
Traveling under or near power lines with no load
Equipment traveling under or near power lines with no load is covered at 1926.1411. The minimum clearance distances in Table T must be maintained. For traveling in poor visibility, a dedicated spotter should be used if needed, along with additional precautions.
When cranes are operating near overhead power lines, the crane, load line, or load could come into contact with the lines. If that happens, the electric current will pass through the equipment to the ground.
Anyone touching the crane in this situation will act as a ground, and the electric current will pass through the person. Even if the person doesn’t touch the equipment, the ground near the crane will be energized and present an electrocution hazard.
The Occupational Safety & Health Association (OSHA) refers to this hazard as “touch potential.” Touch potential is the voltage between the energized object and the feet of a person in contact with the object. It is equal to the difference in voltage between the object and a point some distance away.
Note that the touch potential could be nearly the full voltage across the grounded object if that object is grounded at a point remote from the place where the person is in contact with it. For example, a crane that was grounded to the system neutral and that contacted an energized line would expose any person in contact with the crane, or its uninsulated load line, to a touch potential nearly equal to the full voltage of the power line.
People should avoid approaching or coming into contact with any equipment that is operating, or any load being moved, near power lines.
If a crane comes into contact with a power line, the current will pass through the equipment to the ground. This unintentional grounding, more commonly known as a ground fault, enables voltages to be impressed on the “grounded” object that is faulting the line. A person could be at risk of injury during a fault simply by standing near the grounding point.
The Occupational Safety & Health Association (OSHA) refers to this hazard as “step potential.” Step potential is the voltage difference between the two feet of a person standing near an energized grounded object. It is equal to the difference in voltage, given by the voltage distribution curve, between two points at different distances from the electrode.
OSHA recommends that anyone who is not directly involved in the operation being performed should keep away from areas where hazardous step or touch potentials could arise. Anyone on the ground in the vicinity of transmission structures should stay at a distance where step voltages would be insufficient to cause injury.
A common method of grounding, which the Occupational Safety & Health Association (OSHA) recommends in 1926 Subpart O — Motorized Vehicles, Mechanical Equipment, and Marine Operations for work near an electrical charge, includes:
It’s important to understand that work being performed near transmitter towers or power lines (where an electrical charge can be induced in the equipment or materials being handled) must have precautionary measures implemented to dissipate induced voltages before work is performed. Being aware of the limitations of grounding is key.
Limitations of grounding
According to the preamble to Subpart CC (page 47958 of the Federal Register dated August 9, 2010), “OSHA is aware that employees are exposed to serious electric shock hazards when they are attaching grounds in accordance with 1926.1408(f). For example, when attaching the rigging to the load or the ground to the crane, the crane and load will be energized.
“OSHA views this condition as a recognized hazard and expects employers to ensure that employees are adequately protected when they are attaching grounds. Employers who fail to properly protect their employees in this regard will, in appropriate circumstances, be subject to citation under the General Duty Clause (sec. 5(a)(1)) of the OSH Act.”
Recommended evacuation procedures
Deciding whether to remain inside the cab or evacuate after power-line contact is important, especially where there is an imminent danger of fire, explosion, or other emergency. According to OSHA, to protect crane operators against electrical shock, the following procedures are recommended: