2.3.2 Mains Electricity

• How are most electrical appliances connected to the mains?

  Three core cables.
• What is the colour of the live wire?

  Brown.
• What is the brown wire called?

  The live wire.
• What colour is the neutral wire?

  Blue.
• What is the blue wire called?

  The neutral wire.
• What colour is the earth wire?

  Green and yellow stripes.
• What is the green and yellow striped wire called?

  The earth wire.
• What does the live wire do?

  Carries the alternating potential difference from the supply.
• What does the neutral wire do?

  Completes the circuit.
• What does the earth wire do?

  Protects the wiring and acts as safety against the appliance becoming live.
• Which wire is at 230V?

  The live wire.
• Which wires are at 0V?

  The neutral and earth wires.
• What is the voltage of the live wire?

  230V.
• What is the voltage of the neutral and earth wires?

  0V.
• When would the earth wire carry a current?

  During a fault.
• Your body and the earth are at 0V, so touching a live wire creates a large potential difference across your body, allowing a current to flow through you.
• Current from the live wire can cause a large electric shock that may lead to injury or death.
• Even if a plug socket or light switch is turned off, there is still a risk of electric shock due to potential difference in the live wire.
• Any connection between live and earth can be dangerous, as it can create a low resistance path to earth, resulting in a huge current flow that could cause a fire.