Combined ScienceCode 5129
Electrical safety
What this topic asks you to be able to do
- State the hazards that come from: (a) insulation that is damaged (b) cables that overheat (c) damp conditions (d) excess current caused by overloading plugs, extension leads, single and multiple sockets on a mains supply
- Explain what trip switches and fuses are used for and how they operate, and choose suitable trip switch settings and fuse ratings
- Account for the sequence of events when a live wire makes contact with an earthed metal casing
- Account for why, in an electrical appliance, the exterior shell must be either earthed or non-conducting (double insulated)
- Understand that a mains circuit has three wires, namely the live (line) wire, the neutral wire and the earth wire, and explain why a switch needs to be placed in the live wire so the circuit can be switched off safely
- Account for the reason fuses and circuit breakers are placed in the live wire