The inside of a plug showing the positioning of the earth, neutral and live wires, as well as the fuse and cable grip.

A plug connects a device to the mains electricity supply.

The cable between the device and the three-pin plug contains three copper wires that are coated with plastic.

  • copper wires are good conductors;
  • plastic is a good insulator.

Each part of the plug has a function.

Features of a plugFunction
Outer insulationAll three wires in the cable are bundled together and there is extra plastic insulation wrapped round them all for safety.
Cable gripThis holds the cable tightly in place so that wires do not become loose.
Live wireCopper wire coated with brown plastic along which the current enters the device.
Fuse A glass or ceramic canister containing a thin wire that melts if the current gets too high.
Neutral wireCopper wire coated with blue plastic that also connects to the cable in the wall and completes the circuit.
Earth wireCopper wire coated in striped plastic that provides a path for current to flow from the case of the device to the ground if there is a fault.

One way of remembering the position of the wires is:

BLue Bottom Left
BRown Bottom Right