To do its work, electricity has to flow in a circuit. In household terms, it flows up the wire from the substation to the meter in the house, from the meter to the consumer unit (the up-to-date term for the fuse-box), from the consumer unit to the various power points and light liftings, through the appliances and back by a parallel route to the source.
This circuit involves two wires. The incoming flow is carried in the live wire – red in fixed wiring, brown in electrical flex – and the return flow in the neutral wire ЎЄ black in fixed wiring, blue in flex. Household wiring also has a third wire: the earth connection, which is coloured either green or green and yellow. The earth connection protects us, the consumers, by providing a safe pathway for electricity to ‘escape’ if something goes wrong.
The earth has an almost infinite-capacity to absorb electricity. Without an earth connection, it would be possible for a fault to occur so that the body of, say, an electric kettle was connected to the live supply. A person touching the kettle would receive an electric shock – perhaps a fatal one. By connecting the body of the kettle to earth, the dangerous live connection is short-circuited. In practice, the fuse in the plug would blow almost at the instant the fault occurred, cutting off the live feed.
The Wiring Regulations
The Wiring Regulations are a guide to good wiring practice, to ensure that it can safely meet the demands placed on it. They cover all aspects of wiring. Anyone can buy a copy, and most public libraries will have them, though you may find them difficult to understand unless you already have a good deal of relevant expertise.
Some electrical wholesalers offer guides to the Regulations – though these are aimed at electrical contractors rather than d-i-yers – and may summarise relevant parts of the Regulations in their catalogues.
Working safely with electricity
It cannot be said too often that electricity is dangerous. Before you start work on any part of your wiring, switch off at the mains. Switching off at a wall switch is not enough. If it’s essential to keep some circuits working while you work on others -to use an electric drill, for example -it is possible to remove the fuses or switch off the circuit breakers for just some of the circuits. But you must be quite certain which fuses or circuit breakers are involved. In older homes particularly, this may not be obvious. Extra power points may have been fitted, for example, and you should not assume that all the power points in one room are necessarily connected to the same-ring main. At all times, err on the side of safety: if in doubt, stop. Get advice from a qualified electrician or from your local electricity showroom. never take chances.