Mains electricity

• Most electrical appliances are connected to the mains using three-core cable
• 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 neutral 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 earth is about 230V. The neutral wire is at, or close to, earth potential (0V). The earth wire is at 0V, it only carries a current if there’s a fault
• People's bodies are at zero volts. If someone touches a live wire, a big potential difference will act across their body, causing a current to flow through them. They will suffer an electric shock, which could be fatal.
• Dangers of providing any connection between the live wire and earth

  If a live wire inside the appliance touches a neutral wire, a very big current passes between the two wires at the point of contact. This is called a short circuit.