Fuses and circuit breakers - Domestic electricity – WJEC - GCSE Physics (Single Science) Revision - WJEC - BBC Bitesize

Fuses and circuit breakersFuses and circuit breakers protect electrical circuits and appliances.FusesThe fuse breaks the circuit if a fault in an appliance causes too much current to flow. This protects the wiring and the appliance if something goes wrong. The fuse contains a piece of wire that melts easily. If the current going through the fuse is too great, the wire heats up until it melts and breaks the circuit.Fuses in plugs are made in standard ratings. The most common are 3 A, 5 A and 13 A. The fuse should be rated at a slightly higher current than the device needs:if the device works at 3 A, use a 5 A fuse if the device works at 10 A, use a 13 A fuseCalculating the value of the fuse requiredThe equation P = I × V can be rearranged to find the current if the power and voltage are known.I = P ÷ VFor example, what current flows through a 1.4 kW electric fire at a of 230 V? Remember that 1.4 kW is equal to 1,400 W.Current = 1,400 ÷ 230 = 6 AThe best fuse to use in this example would...