replace an old brass light switch Ask questions and find answers to many subjects relating to electrics and electrical work

[john1973]

I have an old bungalow that has old brass toggle switches as the light switches. I want to replace these with modern fittings. The face of the old fitting is easy enough to take off and rewire but the back box is old and doesn't have anywhere for the new switch to bolt into.

Is there any way of adding a new switch without having to dig a hole in my wall to replace the conduit box with a proper back box?

[BLAKEY1963]

JOHN1973
u could use a plastic surface patress.

BLAKEY1963

[john1973]

i really want the facing of the switch to be as flush with the wall as possible.

[rflight]

Check the size of the old back box as sometimes they will be larger than a new style box, if so then purchase a new steel back box and insert it inside the old box and secure with a couple of screws. This can be tricky as the cable can get in the way, try pushing this back up the conduit until the new back box is fitted.

[333rocky333]

The 12mm metal switch box may fit inside with a bit of persuasion as said.

If not
Do you know if the old metal box is earthed?
you can buy a single size metal face plate mounting frame it is about 4mm thick and has 4 corner holes to fix to wall ,it is designed for PANEL MOUNTING accesories.
You can carefully flush in totally the 4mm or leave slightly surface and just paint in the edge white.
Made by mk

It has 4 - 3.5 mm fixing lugs , use the two for fixing the switch, and one of the other lugs to attach an EARTH which must be done.
They need to be level as they are not adjustable.

You may still need to break out some of the old box to accomadate the back part of the switch but you will need to attach the earth from the plate to the old box somehow,or lug on to one of the old boxes threaded holes.
AS the pipe to it is probarly used as the earth.

There is also a 10mm wide plastic box available

Or just cut the box out carefully and replace, depending on what you have, if its the old toggle box it is screwed onto the pipe, you may need an adapter though to join the box to the pipe for earth continuity though, reguiring a 25mm deep box.

Even with a plastic switch the metal box or frame still needs earthing due to the metal screws or future replacement.


You can also buy plastic decor plates that go behind the switch they are about 3mm thick but are about 30mm larger all round.
You can cut a box in then fill round it and they will cover the damage till you decide to decorate.
or buy a roll of border and do a feature round the switch to cover the repair.