9th Sep '25

Safety Devices

If an electrical fault causes too great a current the circuit should be switched off by a fuse or a circuit breaker.

A fuse is a wire. It is placed in with the wire. When a current flows through it, it gets . If the current becomes too the wire . This puts a in the circuit, so the current can no longer . This appliances from damage.

The the wire the more current it can carry. Common values of fuses are: 3A, 5A, 10A, 13A. When picking a fuse rating we need to select the value that is the normal amount of current drawn by the device.

Use the above to fill in the table:

Appliance Normal
Current
(A)
Fuse
Required
(A)
Laptop 1.6
Phone Charger 0.1
Kettle 12
Desk Lamp 2.5
Toaster 4.3
Hair Dryer 6

A circuit breaker performs a similar function using magnetism. This allows it to be 'resetable' and so is often given the name of a 'trip switch'.