Hazards when using a mains supply
- Damaged insulation — When insulation is damaged, conductors and wires could be exposed. Contact with this leads to electric shocks, and deaths.
- Overheating cables — Because of the high current, it could cause overheating, leading to electrical fires.
- Damp conditions — Water is a conductor. When wet skin touches electricity, they would have an electric shock. When in wet conditions, people nearby could get electrocuted.
- Excess current from overloading of plugs, extension leads, single and multiple sockets
A mains circuit consists of a live wire (line wire), a neutral wire and an earth wire. A switch must be connected to the live wire for the circuit to be switched off safely. This ensures no current flows through the appliance.
Fuses
- Use: A fuse protects the components in a circuit from overheating.
- Operation: Fuses allow a certain amount of current to flow through it. When it reaches its maximum value, the fuse will melt and the circuit will break.
- Appropriate fuse ratings: Around 5A.
Trip switches
- Use: When the current is too high or when there is a fault in the wiring, it turns off the circuit to stop current from flowing.
Casing
The outer casing of an electrical appliance must be non-conducting (double-insulated) or earthed.
- Double insulation is an additional barrier on an electrical device.
- Earthing (via earth wire) allows any leakage of electric current to be transferred to the ground.
They both prevent electrical shocks.
A fuse without an earth wire protects the circuit and the cabling for a double-insulated appliance.