Fuses

1.   Draw the symbol for a fuse.

2.   By law, the plug of every electrical appliance sold in the UK must have the correct size of fuse fitted. Explain the purpose of the fuse in the plug.

3.   What is the danger if too large a fuse being used in a plug?

4.     Fuses for plugs are most commonly available as 3 A, 5 A and 13 A values.

(a)   Calculate the current that is normally used by the following appliances and then state which size fuse would be used in the plug. All the appliances are connected to the mains at 230 V.

(i)    A 60 W table lamp.

(ii)   A 2kW electric heater.

(iii)  An 800 W microwave oven.

(iv)  A 500 W fridge-freezer.

(b)   Why would a 3 A fuse be unsuitable for an 850 W mains sandwich toaster?