Fuses and Circuit Breakers

Earthing and fuses prevent fires and shocks

• If a fault develops in which the live somehow touches the metal case, then because the case is earthed, a big current flows in through the live, hrough the case and out down the earth wire
• This surge in current blows the fuse (or trips the circuit breaker) which cuts of the live supply
• This isolates the whole appliance, making it impossible to get an electric shock from the case…