What are the requirements for a confined space warning sign?

Warning signs must be large enough to be noticed by someone who is curious about the space.

The standard does suggest the wording on the sign read: DANGER — Permit-Required Confined Space. Do Not Enter.

OSHA also says an employer does not have to use signs if other methods are used, such as additional training, if they are truly effective in warning all the employees who could reasonably be expected to enter the space and is at least effective as a sign.

An employer could also lock the entrance or have a cover that can only be opened with special tools instead of using signs, if all employees know that they are not to be opened without authorization. And, if they are left unlocked or open for some reason, temporary warning signs would be required.

Even if signs are used, employers might have to train employees who have trouble reading or speaking English so the meaning of the signs are clearly understood.