Mains cables have three wires, each with a different job and a different colour of insulation.
- The live wire is brown. It carries the alternating potential difference from the supply to the appliance. It is at about 230 V compared with earth.
- The neutral wire is blue. It completes the circuit by returning current to the supply. Its potential difference is about 0 V, close to that of earth.
- The earth wire is green and yellow. It is a safety wire that is connected to the metal case of an appliance. It is at 0 V and normally carries no current.
When wiring a plug, each wire goes to its own pin, the cable is held firmly by the cord grip, and the fuse is fitted in the live side.
