Alternating current (AC power) is the typical type of power used in all homes and buildings.


The French heat unit. Used to measure energy levels for Arc Flash boundaries and proper PPE when working on energized electrical equipment.


The ability of a body to store an electrical charge. Measured in farads as the ratio of the electric charge of the object (Q, measured in coulombs) to the voltage across the object (V, measured in volts).


A closed path in which electrons from a voltage or current source flow. Circuits can be in series, parallel, or in any combination of the two.

Circuit Breaker

An automatic device for stopping the flow of current in an electric circuit. To restore service, the circuit breaker must be reset (closed) after correcting the cause of the overload or failure.

Circuit Breakers

Each circuit group has a switch, which are called ‘circuit breakers’. Labels will usually indicate which part of the house each switch controls. In the event that a circuit is overloaded it could become very hot and pose the risk of starting an electrical fire. The circuit breaker’s job is to stop this happening. If the current flow exceeds the rated amp value of the circuit, the switch is opens, “breaking” the flow of the current, shutting the power off to that circuit in a extremely short amount of time, stopping any chance of an accident happening. The circuit can be connected again simply by closing the switch.


For energy to flow to light sockets and power points in your home, it needs to travel through a path or “circuit”. It is called a circuit because it contains two wires: one that delivers electricity from the generator to the destination (this is ‘active’) and one that carries electricity back to the generator (this is ‘neutral’), thus completing the “circuit”.


Any material where electric current can flow freely. Conductive materials, such as metals, have a relatively low resistance. Copper and aluminum wire are the most common conductors used in the electrical trade.

Current (I)

The flow of an electric charge through a conductor. An electric current can be compared to the flow of water in a pipe. Measured in amperes.