Free SAS Urban Survival Handbook by John Wiseman Page A

amp
Showers: 30 amp
Oven (up to 12 kW): 30 amp
Oven (over 12 kW): 45 amp
Storage heaters: 20 amp

REMEMBER
     
    Always keep a flashlight near your electricity meter. If it is in a dark cupboard, this will help you see what you’re doing. If you need to switch off the power at night, you will need to avoid fumbling around. DON’T use a candle if the fuse box/consumer unit is near your gas meter!
     

CABLES/FLEXES
     
    Live, neutral and earth wires are colour-coded for identification to make sure that the correct electrical connections are made. Unfortunately, colour coding is not standard around the world, but it is beginning to be. This can never take account of strange ‘bodged’ wiring jobs people may have created.

Main circuit wiring (cable)
     
    Old rubber sheathing is still common and should be treated with suspicion. Rubber degrades with age and crumbles. But even modern wiring (on supply cables) will have a red live, a black neutral and a green-and-yellow earth. In practice, the earth wire is often unsheathed in the centre of the cable. Special green-and-yellow sheathing is sold for you to cut to length, to sleeve sections of the earth which are exposed when making connections. DON’T use spare pieces of black or red sheathing. DON’T use electrical insulating tape.

Appliance wiring (flex)
     
    The live is always brown, the neutral is always blue, the earth is always green-and-yellow (when there is an earth wire).
    Old appliances—which should really be rewired and updated by an expert (or discarded)—will probably have a red live, a black neutral and a green earth. If the wires are old, the colours of the sheathing may have faded or discoloured. DO NOT GUESS! Old rubber insulation is, by now, not safe.

WARNING
     
    When connecting wiring with screw fittings, DON’T over tighten the screws. To do so may sever individual strands of multi-stranded flex. These may become dislodged and form an unwanted and dangerous connection. With cable or singlestranded flex, over tightening the screw may flatten (or even sever) the wire. Heavily-flattened wire may act like a fuse, with a reduced capacity for carrying current. It can overheat, may burn out and may start a fire.
     

Types of domestic cable
     
    On a 240-volt supply, the lighting circuits are generally formed by 1.0 mm 2 twin-and-earth (a plastic casing housing three single-strand wires—one sheathed red, one black and one unsheathed) Each wire is about 1 mm in diameter.
    The power cable for the main power (socket) circuits is very similar, but of a heavier weight.
    On special circuits for ovens, electrical heating installations or shower heaters, even thicker cables may be used.

WARNING
     
    No mains wiring alterations or installations should be attempted by anyone who is not qualified to do so. Because of the dangers, in some countries such as Australia, severe restrictions are imposed on the type of electrical work that you can do yourself.
     

Types of flex
     
    Flexes may contain two sheathed wires—brown (live) and blue (neutral)—in an outer casing OR three wires, if a yellow-andgreen earth wire is included. Sometimes a thin two-core flex may have no outer casing—but this is only really suitable for wiring battery-operated doorbells.
    Most flexes, inside the internal coloured sheathing, are made up of several thin strands of wire, which gives the flex FLEXibility. When stripping the sheathing from the ends, for wiring a plug, take care not to sever individual strands. Losing one or two may not matter, but if you lose too many the current-bearing capacity of the wire is reduced at that point. This could cause overheating—or even fire.
    When you buy flex , ask the dealer which is the correct one for a particular appliance. There is a rising scale of thickness to cope with different power consumptions. The flex is usually marked with its recommended maximum load.
    When using longer flexes —perhaps an extension lead to a garden tool—you will