Recall the differences in function between the live, neutral, and earth mains wires in a three-core cable.
Identify mains wires by their insulation colours: live wire (brown), neutral wire (blue), and earth wire (green and yellow stripes).
Recall the potential differences of the three wires: the live wire carries about 230 V, while the neutral and earth wires are at or close to earth potential (0 V).
Explain that the live wire carries the alternating potential difference from the supply, the neutral wire completes the circuit, and the earth wire is a safety wire to stop the appliance from becoming live.
Understand that the earth wire only carries a current if there is a fault.
Explain why a live wire may be dangerous even when a switch in a mains circuit is open.
Explain the dangers of providing any connection between the live wire and earth, which can result in a large potential difference across the body and cause a severe electric shock.
