PhysicsCode 5054
Electrical safety
What this topic asks you to be able to do
- State the hazards, when a mains supply is being used, of: (a) insulation that is damaged (b) cables that overheat (c) damp conditions (d) too much current caused by overloading plugs, extension leads, and single and multiple sockets
- Explain how trip switches and fuses work and what they are for, and select suitable values for the ratings of fuses and the settings of trip switches
- Explain what takes place when a live wire makes contact with an earthed metal casing
- Account for why an electrical appliance's outer casing has to be made non-conducting (double-insulated) or connected to earth
- Know that the three wires of a mains circuit are the live wire (or line wire), the neutral wire and the earth wire, and explain why the switch must sit in the live wire if the circuit is to be turned off safely
- Account for the reason fuses and circuit breakers are placed in the live wire