Selecting a replacement light switch
If a switch needs to be replaced, because it is damaged or you require one of a different style, be sure to buy one with the same function. For example two gang, two way. For more information on the types of switch available see our Light Switches article. Also, make sure with a surface mounted switch that it matches the profile of the mounting box. If not, you will need to buy a suitable box as well.
Removing the old light switch
1. Switch off the power at the consumer unit for the circuit concerned. If you have removable fuses at your consumer unit, switch off the power at the consumer unit and remove the fuse for this circuit.
Identifying the wires or cables
4. The simplest way is either to label each conductor with the location of the terminal to which it connects, or to transfer one conductor at a time to the corresponding terminal on the new switch.
6. Earth conductors will not need to be labelled as they all go to the same connection terminal. This may be at the back of the box or, in the case of a metal switch, a terminal provided at the back of the switch plate.
7. If you have more than one gang or switch, be sure to label each set of conductors according to the gang they are connected to as well. With a two gang one way switch for example you would have:
A ‘C’ – common on gang A
A ‘L1’- Live back to the light on gang A
B ‘C’ – common on gang B
B ‘L1’- Live back to the light on gang B
Connecting the new light switch
9. Check each of the conductors ensuring that none are damaged.
10. Reconnect the labelled conductors to exactly match the original wiring.
11. In this example we have a two gang one way switch, and therefore two sets of conductors to deal with. We have a Common, and an L1 for each of our switches (or gangs) A and B
13. Tighten the connection terminal screw to secure this conductor and ensure that it is fully housed and there is no exposed conductor showing. Remove the label.
16. As mentioned earlier, you may have more conductors but follow the process of connecting corresponding labelled conductors to their appropriate terminals.
17. Once all conductors have been inserted into their appropriate connection terminal on the back of the light switch, and all have been properly secured, double check your wiring and connections.
21. Once you are sure that all work has been completed correctly, switch the power back on at the consumer unit. In the case of removable fuses, replace the fuse for the circuit, and switch the power back on. Check that your light switch is working correctly.