What kind of light switch housing is this?

[WillyWarbux]

I'm looking to replace a light switch in my living room as it juts out from the wall, so I opened it up to see what was going on.

There's a really old looking light switch 'box' back there attached onto a piece of wood inside the lath and paster wall. I say box... it's round. My guess is that it's the original hardware from the 1920s when the house was built - but there's plasterboard that's been installed at some time more recently. The right side of the housing is about level with the wall - which means when the accompanying metal plate is attached, there's a about a 5mm gap. (see pics)

I thinking the best idea would be to remove it and put in a new back box but I can't seem to move the housing. Took out a couple of screws at the back, but its solid. There's a thread at the top which you can see in the picture. I'm not sure how I could turn/unfasten anything though without taking the plasterboard off?

Any help or pointers? Hopefully I'm just overlooking something simple. cheers.

 

[AndyPRK]

It’s a conduit box. Leave it in there. It makes rewiring easy

 

[flameport]

I'm not sure how I could turn/unfasten anything though without taking the plasterboard off?

You can't, the conduit is threaded and is screwed into the box.
It's an old version of one of these: https://www.screwfix.com/p/deta-1-way-20mm-terminal-conduit-box-galvanised/1599J

I thinking the best idea would be to remove it and put in a new back box

Probably, but unless you want a pile of damage and disruption, leave it there.
Removal of at least some of the wall is inevitable, and the thread may not be a metric one.

It's not 1920s either. 1960s or later is more likely.

 

[chivers67]

The only way of removing that without disruption is to pull the cable up/out enough to cut it with a multi tool with a metal cutting blade or angle grinder but really not worth the grief. Then hope the conductors push back down!

 

[JohnD]

The wires look to me like later PVC singles that have been pushed down older steel conduit to save chasing the wall. If you look in the floor above you will be able to tell if old conduit has been reused or if it was originally like that. The conduit is heavy threaded steel and it would have been a costly job. I have seen it in houses wired in the 1920's, but the actual wires you show look to me like 1970's or thereabouts, but thin black enamelled slip conduit was more usual then so I think it is reused old material.

That heavy grade is still used in industrial installations sometimes.

 

[SUNRAY]

The only way of removing that without disruption is to pull the cable up/out enough to cut it with a multi tool with a metal cutting blade or angle grinder but really not worth the grief. Then hope the conductors push back down!

I agree, it look like there may be another conduit to the left and a bit of split tube out through the back, so a lot of cutting and damage before being able to use the thread.

 

[WillyWarbux]

Thanks so much everyone for your knowledgable replies!

So... looks like I probably want to leave it there, in which case. How would you go about making the light switch fit/look better? I've attached a new photo. A bit of caulk would be fine, but its quite a large gap really.

Can you get slightly deeper light switch faces?

 

[SUNRAY]

Would these help

Schneider Electric Lisse 1-Gang Spacer White - Screwfix

Order online at Screwfix.com. 1-gang spacer made from durable, high quality moulded urea with anti-microbial properties. Ideal for new construction and refurbishment projects. Concealed fixings. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

https://www.cef.co.uk/catalogue/products/614431-1-gang-square-spacer-10mm-white-plate?gad_source=1&gclid=CjwKCAiA3JCvBhA8EiwA4kujZsbMQTs7fYjEODZk71x74xls3igjirAkjisg92K2DRwl7SwAUbPrvBoCqDcQAvD_BwE&gclsrc=aw.ds

It may be possible to position it behind the adapter plate.

 

[flameport]