Three-pin plug in an electrical socket. Pushing the socket switch closes the circuit allowing connection of an electric appliance to the UK's 240 volt alternating current power supply. The cable carries live, neutral and earth wires from the appliance, which terminate at three pins. The plug also contains a fuse, a fine wire which protects an electrical appliance from overload. If the current rises too high the fuse melts and breaks the circuit. The earth wire connects the appliance to the ground and in the event of a fault in the appliance the current flows to earth causing no harm to the user.