Fuses & earthing

Electrical Overloads & Surges

Electrical surges (sudden increases in current) can occur due to:

• Changes in the circuit, such as an appliance suddenly switching off.

• A fault in an appliance that causes too much current to flow. These surges can lead to:

• Wires overheating and melting, which can cause fires.

• Electric shocks if the appliance is faulty.

How Fuses Work

Fuse Ratings

Fuses should be rated just slightly higher than the appliance's normal operating current.

If an appliance normally operates at 4A, a fuse rated around 5A would be used.

• The larger the current, the thicker the wire in the cable is needed to safely carry the current without melting.

Earthing

Double Insulation

• Some appliances are double insulated and don't need an earth wire:
  • Double insulation means the appliance has a plastic casing and no exposed metal parts.
  • Double insulated appliances only need two wires: the live wire and the neutral wire (no earth wire is needed).
  • Two-core cables carry only the live and neutral wires.

Circuit Breakers

• Circuit breakers can be used instead of fuses in household wiring.
  • They serve the same purpose as fuses but are more convenient because they can be reset instead of needing replacement.
  • Circuit breakers also react faster than fuses, providing better protection against surges.