Cannot secure switch to backbox

[Mr Sparkle]

I have a backbox, which appears to be metal.

However it has plastic lugs on the sides in order for you to insert your 3.5 screw

However whenever i try to screw the faceplate to the backbox, it grips/screws for a little then nothing.

So i am left with a faceplate the protrudes

Does anyone know how i can rectify this

The property was built in the early 60s and i assume that this may be an original backbox

 

[flameport]

Are these new screws or the ones that were there originally?

Old boxes may be 4BA, which is slightly larger than modern M3.5

 

[Mr Sparkle]

That could be it.

I used new screws

Can these screws be sourced at a shop such as screwfix as opposed to ordering online?

https://www.spaldingfasteners.co.uk/4ba-a2-stainless-steel-round-slotted-head-machine-screws/

 

[JohnD]

please post a photo of the inside of the wall box (and the old switch) and, especially, the old screws, showing any wear on the threads.

plastic tabs are unlikely to be BA threads.

 

[AndyPRK]

Use old screws.

Probably screwing into nylon

 

[crystal ball]

I bought some BA screws from an old style hardware shop, he had some odd boxes covered in dust, probably not feasible at the moment

 

[sparkwright]

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[sparkwright]

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[sparkwright]

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[sparkwright]

Waste of time.

Once those nylon lugs have gone, they have gone.

Changing the box is the best option, though you may not want to do that.

Usually if you remove the nylon lugs, you will find a hole in the back of the box to reveal brickwork.

Determine where the holes need to be, and drill the brickwork with a 5mm masonry bit, and insert 5mm wall plugs (used to be yellow).

If you have a 3.5mm rethreading tool, thread these plugs holes.

Then get some new, long 3.5mm machine screws to hold swirch plate.

Carefully measure what screw length you need. If too long, disaster will occur.

 

[AndyPRK]

They maybe not be gone. If using too small screws that’s maybe the problem.


See at 6 mins.

And interesting idea.

 

[Mr Sparkle]

please post a photo of the inside of the wall box (and the old switch) and, especially, the old screws, showing any wear on the threads.

plastic tabs are unlikely to be BA threads.

That's going to be difficult as i do not have access at present and the person who does have access is scared of prying the switch from the backbox and taking a pic.

She said something about a fear of 240v and possible electrocution

 

[Mr Sparkle]

@sparkwright top man!

Just so that i have it right, after inserting the yellow plugs, i should use the 3.5 rethreading tool inside the yellow plug?

If the screw is too long, what could happen?

Use old screws.

Probably screwing into nylon

I threw out the old screws.. i assumed that all back boxes (especially in a home built in the last 60 yrs) would use 3.5 screws

 

[Mr Sparkle]

See at 6 mins.

And interesting idea.

Thanks for the video. Very interesting indeed

However, what's with the mellow dramatic music that's playing in the background?

 

[crystal ball]

Has the property been rewired, if not there is a good chance the lights will not be earthed, could cause some issues if metal lights or switches are fitted