Metal Light Switch Faceplates

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Hi,

This has most likely been answered countless times before, but I'm looking to clarify the simplest way to replace a plastic light switch with a metal one.

The current set up is a wall mounted plastic faceplate which I intend to replace with a flush brass plate. Behind the plaster, the metal conduit is acting as the earth which is attached to a small round, metal, mounting box.

In order to safely earth the new faceplate will I have to replace the round box with a new square mounting box which is attached to the conduit or can an earth wire be attached to the terminal on the switch and subsequently attached to the round box/conduit?

Obviously i'm looking for the least amount of mess etc as i've just re plastered the walls.

Any help would be appreciated.

Thanks.
 
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You'll be hard pushed to get the conduit boxes out of the wall without making a right mess of the plaster!

Can the new face plates sit within the existing box? If so you'll still need to drill a hole in the conduit box, thread it so you can get a screw in, then run a fly earth with a crimped lug from the screw to the metal plate.

Hmmm, maybe better to stick with the plastic switch plates...

SB
 
SB, apply is appreciated.

I stupidly didn't even think about it fitting within the existing box! It's around 2/3mm too big to fit inside! Looks like the plaster is coming off!

I take it it's a simple case of unscrewing the old box and replacing it with a new square box ensuring that the conduit is correctly attached to the box?

Thanks.
 
Do you mean that your cables have only 2 wires in them - red and black, and the metal conduits have a separate wire (steel?) attached to them (you can probably see it if you look in the loft. If this is the case, I would have a PIR done first. Ideally, you should have all the electrics, plumbing, gas done before plastering.
 
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There's no issue in taking a bit of plaster off the wall and re plastering over it. It's an easy job.

I simply wanted to check if there was another way to do it before i took it off. There are 3 wires with red sleeves, no separate earth wire.
 
I take it it's a simple case of unscrewing the old box and replacing it with a new square box ensuring that the conduit is correctly attached to the box?
No. This is likely to make a huge mess of the wall.

If the old box is screwed onto the metal conduit, you won't be able to rotate the box without pulling the conduit away from the wall, which will remove most of the plaster above the light switch position.

Alternatively, you may find that the box won't unscrew because it has been there for 40 years and has rusted on. If this happens, cutting the conduit is the only option. However that will leave you with an unthreaded end and no space to get tools in to cut a new thread on the end.

Or the conduit isn't actually a threaded type, but is just loosely fixed. In this case the conduit cannot be used as earth, so a metal switch cannot be fitted.

Then there is the possibility that it is imperial conduit, not metric.
 
No. This is likely to make a huge mess of the wall.

If the old box is screwed onto the metal conduit, you won't be able to rotate the box without pulling the conduit away from the wall, which will remove most of the plaster above the light switch position.

Alternatively, you may find that the box won't unscrew because it has been there for 40 years and has rusted on. If this happens, cutting the conduit is the only option. However that will leave you with an unthreaded end and no space to get tools in to cut a new thread on the end.

Or the conduit isn't actually a threaded type, but is just loosely fixed. In this case the conduit cannot be used as earth, so a metal switch cannot be fitted.

Then there is the possibility that it is imperial conduit, not metric.


Yes!!!

And not only that. The installation might be quite old. Better have it checked.
 
To clarify things, if the end was unthreaded, surely you can still bond this to the new back box by setting the box so that the conduit passes through the top of the box and securing accordingly or is this not the case?

Having checked other threads, this seems to be the case.

I appreciate the help.
 
To clarify things, if the end was unthreaded, surely you can still bond this to the new back box by setting the box so that the conduit passes through the top of the box and securing accordingly.
Please explain "securing accordingly".
 
To minimise disruption to plastering etc. Sink a new box immediately below the existing. Extend existing wires by using Crimps and add earth conductor as described above.

Existing box can then be covered over.
 
To minimise disruption to plastering etc. Sink a new box immediately below the existing. Extend existing wires by using Crimps and add earth conductor as described above.

Existing box can then be covered over.

I wouldn't want to cover over the screwed earth termination.
 
Is this domestic?

If so, it sounds like the installation is long overdue for an assessment of its actual condition.
The OP does not appear to understand the implications of what he is proposing and once again, safety takes second (fourth) place to cosmetics.
 
The OP does not appear to understand the implications of what he is proposing and once again, safety takes second (fourth) place to cosmetics.
And never explained how he would fix the conduit to a new box.

I think it's a bit, actually more than a bit, off for NICEIC to make a documentary about a fatal accident and use it as a bl**dy advert. :evil:
 
The simplest, quick fix method would be to fit a wooden plinth around the switch - if the op doesn't mind this.

Fix a regular 16 mm metal plaster depth flush box onto the existing conduit box. Use metal screws to maintain earth continuity. Make a 20 mm hole in the back box, and FIT A 20 mm GROMMET.

Buy a wooden switch/socket surround. B&Queue used to do them. If you can't buy one make one. Needs to be 16-20 mm thick.

Sit the surround onto the plaster depth box.

Fit light switch, and provide an earth wire from the new switch box to the new switch plate.

Check earth continuity.

The wooden switch surround could be a stain and varnish affair, or painted white or the same colour as the wall.

Make a note of where the wires go before disconnecting the old switch.
 

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