Movable screw posts on light switch / mains socket backing boxes

"NY" snipped-for-privacy@privacy.invalid wrote in news:qdrfko$m05$ snipped-for-privacy@dont-email.me:

Part stripped threads by the sound of it and screws too short.

Use longer screws. Don't overtighten.

Bill

How odd, I don't think I've had that issue. They are surely either captive or moulded in. Most of my problems with light fittings and switches are that the plastic ones tend to be so brittle they crack as you do that final quarter turn.. grin. Brian

My guess that the back boxes are set too far back from the surface of the wall and the screws are too short for the task, especially true where a wall has been tiled. I learnt a long time ago to have a supply of longer screws.

Agree with the idea of longer screws but it sounds like you have cross threaded the screw holes in the back box. A re-threading tool should help to restore the threads but in my experience this is a once only solution. On ones that I have re-threaded the screws have gone in and gripped but generally the result is quite a sloppy fit and certainly looks like it will not take another re-thread. One possible solution to stripped threads that I have considered is using anchor nuts but don't know if you can get 3.5mm. The fine threads on back box screws are notorious for cross threading the ones I prefer are the type that have the protruding core diameter before the start of the thread, these I find easier to centre and less prone to cross thread.

Richard

Quess you mean plasterboard switch boxes, you could slide the screw post forward and put some tape behind it and don't push too hard on the screw until it catches the thread.

That was actually the quarter turn *after* the final quarter turn!

Dunno where you found a box like that, Adjustable lugs are designed to allow a switch to be set square in a squint box. Not to move away from the fitting.

Most these days have one fixed, one adjustable. Do the adjustable one first. A torch may help to see things.

Yes that's what I'm going to do: either tape or glue the post in the forward position and check that the screw (OK, bolt) threads itself cleanly into the post (without cross-threading) with the faceplate removed, before fastening it normally.

Sod's Law: it would be the three-gang two-way switch that has the fault, so there are a *lot* of very stiff wires to cram back in as I push the faceplate back into place.

Why is it that backing boxes are designed with the captive nut on a movable slide rather than being securely moulded to the side of the box? It means you have to use much longer screws than normal to account for the nut retreating as soon as the screw touches it. All the boxes I've seen have either had a metal or plastic slide which is separate from the metal or plastic of the box, and rather loosely attached so it is prone to sliding.

It's so you can set the faceplate horizontal even if the backbox is slightly skewed in one plane or another.

Well there are these

However for a pro bodge job on a back box with a knackered lug that will not rethread you simply strip out the cores of some .75mm flex and wrap them through the hole several times before refitting the socket.

I've got some 3.5mm nuts. Just superglue to the back of the lug.

Handy for old boxes with BA threads.

as expected, silly price

Neater than using a woodscrew.

NT

You need to be accurate when glueing.

And then there is the other bodge when when lug is missing.

snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@googlegroups.com:

Squeeze the lug with some grips to slightly squash the hole.

Shouldn't there be some expanding foam too, just to be sure?