A-Z of DIY & Building Guides How To Fit A Dimmer Switch

Date Published:

20/05/2009

Step Two:

Use a small screwdriver to undo the two screws holding the existing switch plate onto the switch box.

Single switches are wired to the ring circuit by two-core and earth cable. Changing the plate is simply a matter of unscrewing the small screws in the terminals, removing the wires and connecting them to the new plate using exactly the same terminals.

If you’re replacing a two-way switch that has a more wires to connect, either jot down the positions of each wire or transfer one wire at a time to the new plate to avoid confusion.

Step Three:

Make sure the wires are all firmly secured and bend any extra sheathed cable neatly into the box so that it cannot be trapped by the new cover plate. There should be no more than a few millimetres of bare wire exposed. Screw the cover plate on to the wall box and reconnect the supply. Check the light works.

Step Four:

If the new dimmer switch will not fit into the backbox, you will have to replace it with a deeper version. Turn off the electricity (as in Step One), unscrew the old backbox and use a cold chisel and masonry bit to drill and chip away the wall to make a deeper recess that will hold the new backbox. Add wall plugs and screw to the wall. Fit the dimmer switch as above. Remember to add an earth wire to the backbox and sheath with green/yellow earth sleeving.