The earth wire is a crucial part of the home electrical system and is designed to protect against electric shock. If faults occur in the electrical system, the electricity will flow to earth by the shortest and easiest path. The shortest path is through a circuit breaker or fuse, which will break the electrical circuit. The earth wire should help stop electricity passing through your body if you have an electrical accident.

The earth wires from power points join to a main earth wire, which is attached to a metal pipe and/or special metal electrode (metal stake) driven into the ground. It is important that the earth wire is correctly wired and working properly, and that all appliances and building wires are in good condition. If an earth wire within an appliance is not connected and a loose active wire touches the metal casing, electrocution may occur.