Topic 2 - Mains Electricity

• Three core cable

  How appliances are connected to mains electricity
• Wires in three core cable

  • Live wire
  • Neutral wire
  • Earth wire
• Live wire


  Carries a potential difference of around 230 volts from the supply
• Neutral wire


  Completes the circuit with the live wire, has a potential difference of around 0 volts
• Earth wire


  A safety wire, connected to the ground
• Function of earth wire

  If the live wire comes loose and the metal case becomes live, the earth wire provides a path for a large current to flow to the ground, causing the fuse to melt and shut off the current, preventing electric shock
• Mains electricity in the UK is alternating current (AC) with a frequency of 50 Hertz and a potential difference of around 230 volts
• The live wire is connected to a fuse in the plug
• If someone touches the live wire

  A current would flow through the person into the earth, causing electrocution
• Most appliances in the UK are connected to an earth wire