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'.