Where does all that power come from?
We often take electricity for granted. We press the switch on the power tool or jobsite equipment, and it comes to life. But what happens?
To make the tool or equipment work, the current must flow through the wiring in the tool or equipment to the area that needs it (the area of demand). Often, an extension cord is used to connect the tool or equipment to a temporary power source on the jobsite. If this extension cord becomes disconnected from either, the power is interrupted, and the work stops.
Electrical circuits
Electricity travels in closed circuits through a conductor. Anytime a circuit is broken, the electricity can’t flow and stops. In the tool and extension cord example, the tool’s cord and the extension cord are the conductors.
Electrons
The driving force in electricity is the electron. This is a tiny particle with a negative charge. It will flow along a conductor because of what is called electromotive force (EMF). Electrons move from one location to another because of the differential in EMF. Negative EMF flows to positive EMF and vice versa. That’s why lightning occurs: the bolt of lightning consists of electrons moving through the air to the point of differing charges.
Resistance
When electrons are moving through a conductor, they meet with resistance. When water flows through a pipe, the pipe walls contain and slow down the water. The same is true for electrons; the conductor slows them down.
Some materials conduct electricity better than others. Because metal is usually a good conductor, we make wiring from it. Wood is not a very good conductor. Rubber is a poor conductor of electricity.
Voltage
EMF can be considered pressure or a type of force. For example, when a dam is opened, there is the pressure of all the water behind it. That water is forced through the dam opening under pressure. That’s how electrons move along a conductor; the EMF pushes them. The harder they push, the greater the voltage.
Avoid the closed electrical circuit
Electric shock happens when a worker becomes part of the electrical circuit. Take the example of the tool and extension cord. Say the cord is damaged, and the internal wiring is exposed. If you pick up the cord near the damaged area, the electrons can flow through you. You have now become a conductor.
The electrons then move through you to the ground you are standing on. The tool will stop operating since the electricity is going through you, not the extension cord. You will probably stop operating too.