What is the best way of securing the captive nuts on an electrical backing
box for a light switch or mains socket?

I always find that if I unscrew the front screws (eg so I can paint behind
the switch, or to replace a broken switch with a new one) I have great
difficulty in getting the screws to mate with the captive nuts because they
are often not fixed to the backing box but instead slide backwards so the
screw can never mate with the nut.

Even if the screw does mate, it seems not to be secure and once I tighten it
beyond a certain point it starts to jump thread instead of applying enough
force to hold the switch against the wall.

"NY" wrote in :

What is the best way of securing the captive nuts on an electrical
backing box for a light switch or mains socket?

I always find that if I unscrew the front screws (eg so I can paint
behind the switch, or to replace a broken switch with a new one) I
have great difficulty in getting the screws to mate with the captive
nuts because they are often not fixed to the backing box but instead
slide backwards so the screw can never mate with the nut.

Even if the screw does mate, it seems not to be secure and once I
tighten it beyond a certain point it starts to jump thread instead of
applying enough force to hold the switch against the wall.



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

On 12/06/2019 19:16, NY wrote:
What is the best way of securing the captive nuts on an electrical
backing box for a light switch or mains socket?

I always find that if I unscrew the front screws (eg so I can paint
behind the switch, or to replace a broken switch with a new one) I have
great difficulty in getting the screws to mate with the captive nuts
because they are often not fixed to the backing box but instead slide
backwards so the screw can never mate with the nut.

Even if the screw does mate, it seems not to be secure and once I
tighten it beyond a certain point it starts to jump thread instead of
applying enough force to hold the switch against the wall.

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

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"NY" wrote in message
...
What is the best way of securing the captive nuts on an electrical backing
box for a light switch or mains socket?

I always find that if I unscrew the front screws (eg so I can paint behind
the switch, or to replace a broken switch with a new one) I have great
difficulty in getting the screws to mate with the captive nuts because
they are often not fixed to the backing box but instead slide backwards so
the screw can never mate with the nut.

Even if the screw does mate, it seems not to be secure and once I tighten
it beyond a certain point it starts to jump thread instead of applying
enough force to hold the switch against the wall.

On 12/06/2019 19:48, DerbyBorn wrote:


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


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.


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mailto : news {at} admac {dot} myzen {dot} co {dot} uk

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.

Brian Gaff wrote:

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

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

--

Roger Hayter

In article ,
NY wrote:
I always find that if I unscrew the front screws (eg so I can paint
behind the switch, or to replace a broken switch with a new one) I have
great difficulty in getting the screws to mate with the captive nuts
because they are often not fixed to the backing box but instead slide
backwards so the screw can never mate with the nut.

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.

--
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Dave Plowman London SW
To e-mail, change noise into sound.

"Trevor Smith" wrote in message
...
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.

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.

NY wrote:

"Trevor Smith" wrote in message
...
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.

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.

--

Roger Hayter

On 13/06/2019 09:18, Tricky Dicky wrote:
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.

Well there are these

https://backboxsaver.com/

Never used them.

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.


--
Adam

In article ,
ARW wrote:
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.

--
*People want trepanners like they want a hole in the head*

Dave Plowman London SW
To e-mail, change noise into sound.

On Thursday, 13 June 2019 19:43:00 UTC+1, ARW wrote:

Well there are these

https://backboxsaver.com/

Never used them.

as expected, silly price

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.

Neater than using a woodscrew.


NT

On 14/06/2019 00:33, Dave Plowman (News) wrote:
In article ,
ARW wrote:
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.


You need to be accurate when glueing.


--
Adam

On 14/06/2019 14:16, wrote:
On Thursday, 13 June 2019 19:43:00 UTC+1, ARW wrote:

Well there are these

https://backboxsaver.com/

Never used them.

as expected, silly price

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.

Neater than using a woodscrew.

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

5.5mm hole though the back box where the eye of the lug was, stick in a
red rawl plug and use a long 3.5 screw into the red plug.


--
Adam

wrote in
:

On Thursday, 13 June 2019 19:43:00 UTC+1, ARW wrote:

Well there are these

https://backboxsaver.com/

Never used them.

as expected, silly price

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.

Neater than using a woodscrew.


NT


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

On 2019-06-14, ARW wrote:

On 14/06/2019 14:16, wrote:
On Thursday, 13 June 2019 19:43:00 UTC+1, ARW wrote:

Well there are these

https://backboxsaver.com/

Never used them.

as expected, silly price

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.

Neater than using a woodscrew.

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

5.5mm hole though the back box where the eye of the lug was, stick in a
red rawl plug and use a long 3.5 screw into the red plug.

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