Shree Sai Electrical

Light Fitting & Decoration

All Types of Electric Goods Available.

How Does the Lighting Work in Your House?

Not as big a deal to sort out, but first it is important to understand how the lights work in your house. The diagram below shows the circuits involved. (Please note some older houses may be wired differently in junction boxes which will be located under the floor/loft, the principle is the same).

Power comes into the house to your fuse board or consumer unit. The lights are fed from this via (generally) two circuits. One for upstairs lights and one for downstairs. Both of these circuits should be on 5 amp fuses or MCB’s (Miniature Circuit Breakers). This fuse, in theory, allows up to 12 100W bulbs to be used on that circuit, in practice no more than 8 are normally fitted. The cable runs from the consumer unit, to the first light fitting in the ceiling of that floor, it enters the ceiling rose where it is looped in and out to feed the next light, etc etc. At the same time a cable is connected into the ceiling rose to the switch that controls that light. With ordinary “one way” lighting, ie one switch controls only one light,

Removing Existing Light Fitting

When you have removed your existing light fitting and are faced with a mass of cables hanging out of the ceiling, life is a little daunting…But it is not as complicated as it looks.

Identifying the Wires to the Light Switch

When the power is OFF and fuses out, turn off the light switch, ie make sure the switch is in the off position. Now it is a case of trial and error. Hold the red and black terminals of your circuit tester to a red and a black wire that appear in the same cable. (Using the diagram above, this would mean either cable 1, 2 or 3. Then turn on the light switch (With all power off to the lighting circuits, there is no power to the switch). If you have connected to the switch cable, the circuit tester will indicate that you have completed a circuit. If not , it will not move and you try the next set of black and red wires that are in a cable together. When you have identified the switch cable, mark the black with some insulating tape and even put a piece of tape around the cable sheath so there can be no mistake.

Karan Yadav