Electrical DIY Work

SAFETY PRECAUTIONS

1 Electricity can kill. Treat it with respect.

2 If unsure about the safety of any equipment, consult an electrician.

3 Remove plugs before examining equipment and switch off at the mains before working on fixed equipment.

4 Do not overload circuits by using too many adaptors.

5 Do not use wall switches in bathrooms. Have pull-cords.

6 Faulty electrical work is the most common cause of home fires. Do not risk short circuits by using flex with faulty insulation, fixing cables with staples, leaving bare wire at a plug or failing to use earth wires with metal-cased equipment.

7 Use fuses of the correct size.

8 Connect wires to their correct terminals or there could be danger, even when switched off.

9 For an extension, make sure the socket part is on the mains side.

ELECTRICITY MAIN SWITCH AND METER

Electricity comes into the home via a main switch and a meter, with sealed fuses, all provided by the supplier of electricity. The main switch is off when it is down and the electricity supply for the whole house is then cut off. Switching off here is the safety action in an emergency.

The amount of electricity used is recorded by a meter in kWh (kilowatt-hours). The simplest type to read has a row of figures. Ignore fractions at the right and read the five figures from the left. An older type has six dials with hands and each reading 0 to 9. Ignore the one giving tenths. Read the others in turn from left to right. If a hand is between figures, read the lower. Put your readings together as a five-figure number. A disc turning below the dials indicates that electricity is being used.

FUSES AND CUTOUTS

All electrical equipment is protected from overloading and damage by fuses or cutouts. The whole system is protected by the suppliers’ fuse and they must be notified if that fails. Other fuses are in the circuits and are usually located near the main switch. More fuses may be in plugs.

A fuse is a piece of wire that will get hot so that it melts and breaks the circuit if it becomes overloaded. Occasionally a fuse may ‘blow’ for no apparent reason. Turn off the main switch if you examine fuses. A fuse may be

Tools for simple electrical repairs: (top to bottom) pliers and electrician’s wire strippers (both with insulated handles), screwdriver with neon tester (to check if terminal is live), stanley knife. A torch is also very useful, but be sure that it is a rubber one.

Replaced, but if the new fuse blows, the cause of the trouble must be discovered. If it is not obvious, get an electrician.

The basic fuse is a piece of wire between terminals on or in a ceramic block that can be pulled away from the fuse box. Fuse wire can be bought wound on a card, usually in 5 amp., 15 amp. And 30 amp. Sizes. Do not strain new wire between terminals. There should be some slackness. The ceramic part of the fuse may be marked with a figure to indicate the size wire to use, or it could be colour-coded: white for 5, blue for 15 and red for 30 amp. A cartridge fuse is less troublesome to fit. It is a tube containing the wire, with metal ends to fit into spring clips.

Each cartridge fuse is colour-coded: the most common are 3 amp. (red), used for appliances up to 720 watts, and 13 amp. (brown) for those with a range of 720 — 3000 watts.

A 13 amp plug can be fitted with a 3 amp. Or a 13 amp. Fuse. Lightly-loaded equipment, such as radios and clocks, may have 3 amp. Fuses, but fires and other heavily-loaded equipment require 13 amp. Fuses. Some appliances, although they use below 720 watts, still need a 13 amp. Fuse because of the higher starting current required, especially if they incorporate an electric motor.

A circuit breaker may look like a switch or have a projecting knob or button. If it becomes overloaded, the switch jumps to the off position or the button pops out. Both can be reset by moving them back. Brown for the live line, blue for the neutral line and green and yellow bands for the earth line. Twin cables, with only live and neutral lines are used for lighting and some equipment, including that which is double-insulated and marked with a square within a square. For most other equipment it is important for safety that the earth wire is connected at a plug and to a metal part of the equipment.

Modern wiring uses three-pin 13 amp plugs with flat pins. Older circuits may have plugs with round pins, using 15 amp plugs for fires and other equipment with heavy loads, and 5 amp plugs of a smaller size for lightly-loaded equipment.

If new wire is to be fitted to an appliance, make sure the new cable is of the same size and type as the old. Compare the number and size of copper wires. Do not use twin wires where the appliance has an earth connection. For any sort of portable appliance, use flex of the correct size, not cable intended for rigid wiring. If you have any doubt and do not have old cable to compare, tell your supplier what you need the cable for.

Open a plug and check how much of the end of the cable has to be prepared. Cut back the outer insulation. It can usually be split lengthwise and the surplus cut off. Bare the wire ends far enough for them to wrap around screw terminals or fit into those with holes. In most plugs the earth wire has to be

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