Correctly wired three-pin plug, illustration. This plug is used in the UK to connect domestic appliances and tools to the national 240-volt alternating current supply. The live wire has brown insulation, the neutral wire has blue insulation, and the earth wire has green and yellow insulation. The earth wire is an electrical connection between the appliance and the ground. In the event of a fault in the appliance the current flows to earth causing no harm to the user. The live wire is connected through the 3 Amp fuse (right), which melts if there is a current overload, breaking the circuit.