Mains Electricity

• most electrical appliances are connected to the mains using three-core cablle
• the insulation covering each wire is colour coded for easy identification:

  • live wire - brown
  • neutral wire - blue
  • earth wire - green and yellow stripes
• the live wire carries the alternating potential difference from the supply
• the neutron wire completes the circuit
• the earth wire is a safety wire to stop the appliance becoming live
• the potential difference between the live wire and the earth (0V) is about 230V.
• the neutral wire is at or close to earth potential
• the earth wire is at 0V as it only carries a current if there is a fault
• a live wire can be dangerous even when a switch in the mains circuit remains open, as if the circuit became complete, even accidentally, a large potential difference would start and could electrocute someone