Fusing and earthing 0.0 / 5 ? PhysicsElectricityGCSEAQA Created by: nimrahali12Created on: 30-10-16 14:09 Earthing and fuses prevent? electrical overloads 1 of 23 The earth wire and fuse are included in ? electrical appliances for safety and work together 2 of 23 1-If a fault develops in which the live wire somehow touches the metal case , too a great current flows in through? the live wire through the case and out down the earth wire 3 of 23 This surge in current melts the fuse when ? the amount of current is greater than the fuse rating 4 of 23 This cuts of? the live supply and breaks the cicuit 5 of 23 This isolates the whole appliance , making it impossible to get? an electric shock from the wiring in your appliances from getting fried if there is a current surge 6 of 23 Fuses should be rated as near as possible but? just higher than the normal operating current 7 of 23 The larger the current , the thicker the cable you need to? carry it 8 of 23 Thats why the fuse rating needed for cables usually ? increases with cable thickness 9 of 23 Insulating materials make appliances? double insulated 10 of 23 All appliances with metal cases are usually earthed to? reduce the danger of electric shock 11 of 23 What does earthing mean? the case must be attached to an earth wire 12 of 23 An earth conductor can never become live. If the appliance has a plastic casing and no metal parts showing then? its said to be double insulated 13 of 23 Anything with double insulation like that doesn't need an earth wire-just? a live and neutral 14 of 23 Cables that only carry the live and neutral wires are known as? two core cables 15 of 23 Circuit breakers have some advantages over? fuses 16 of 23 Circuit breakers are an electrical safety device used in? some circuits 17 of 23 Like fuses , they protect? the circuit from damage if too much current flows 18 of 23 When circuit breakers detect a surge in current in a circuit , they break? the circuit by opening a switch 19 of 23 A circuit breaker can easily be reset by ? flicking a switch on the device 20 of 23 This makes them more? convenient than fuses 21 of 23 However? A lot more expensive to buy than fuses 22 of 23 One type of circuit breaker used instead of a fuse and earth wire is? residual current circuit breakers (RCCBs) 23 of 23
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