Can anyone identify this item please?

[divingdave24]

Hi there,

I have a light switch wall box that doesn't have the usual metal screw holes as part of its construction. Instead it has a plastic insert that is wedged into position with two metal clamps - and the screws that hold the wall plate in position screw into these plastic bits. They look like this:

Images here

My problem is that the screw thread on one of them has been worn away so the wall plate is loose on one side. I need to replace this item, but I don't even know what its called so its proving difficult to find one anywhere! Can anyone help me to put a name to it please?!

Cheers,
Dave

 

[securespark]

They are plastic lugs. They come as part of the box, they are not available seperately.

That box harks back to the days when lighting circuits had no earth.

The switch would be attached to the metal box via those plastic lugs and the screws would then be isolated from any (potentially live) metalwork.

The best option is to remove the box and replace it with a standard box, but ONLY if your wiring carries a cpc and you have full continuity round the circuit.

Alternatively you could use an M3.5 rethreader to see if this works, or replace the screw with an M4 screw with CSK head or any self tapper that fits through the switch and whose head sits flush with the surface of the switch plate (for aesthetic reasons).

 

[teachergeezer]

Some years ago we used a device that we called a 'top-hat'. This was a tophat shaped piece of metal that screwed into the middle of the back of the metal box, usually with a self-tapper, and had the necessary metal lugs into which you can screw the 3.5mm screws. If you can get hold of them, try your wholesaler, it means you won't need to remove and replace the box. Being metal it also ensure earth continuity is maintained between the back box and the switch screws.

 

[divingdave24]

Thanks securespark and teachergeezer. Both very helpful answers - much appreciated.

teachergeezer - I think I may have found a few 'top hats' inside some of the old wall boxes we're removing (we're renovating an old house) - I'll give them a go.

Either way - at least I now know what I'm asking/looking for, thanks.

 

[JohnD]

I think that's a nice new earth wire I can see in the box, so you might like to just take out the old box and fit a new one. With luck it will be held in place by one or two screws, but run a thin blade round the box to separate it from the plaster (like taking a cake out of its tin) to reduce the amount of plaster that breaks away from the wall.

p.s. I can't see an earth lug in that old box, where are you going to connect the earth wire?

 

[securespark]

I know in an ideal world, the box should always be earthed (that was my top suggestion), but in the absence of earthing the insulated lugs will prevent any contact between the fixing screws and live metalwork.

 

[divingdave24]

p.s. I can't see an earth lug in that old box, where are you going to connect the earth wire?

I came across the problem with the plastic lug as we were getting ready to decorate the room, so this is the first time I've opened this box up since our electricians rewired our whole house last year.

They've connected the earth wire to the actual metal box in the wall. Its held in with a screw. If you look at the bottom picture of the 3 you can see a small hole in the middle of the box, behind the yellow wire. Its screwed there.

 

[pdcelec]

since our electricians rewired our whole house last year.

I take it that it was a cheap rewiring job?

 

[divingdave24]

Not exactly! Why, is that dodgy?!

 

[HannibalSmith]

The switch backboxes are circa late 60's - early 70's...... so they should have been replaced when your house was rewired.