Light switch not working when fitted to the wall

[Gary's]

Hi all
Can anyone please advise, i have fitted a new fused light switch cover in the kitchen as the press switch part broke on the old one, however I wired the new one up and all worked well, but when I screwed it back onto the wall it would not work, took it off the wall and it worked again.

 

[timhoward]

Is anything tripping when it doesn't work?
Is it a fused spur for an appliance like a washing machine or dishwasher, or is it actually switching a light?

In abstract there are a few possibilities:
Damaged cable only working in certain positions?
Poor connections? Something going on with the earthing - is it a metal back box?
A couple of photo's would greatly help you get some useful answers, showing how you've wired it, and the box it's going into.

 

[juanmanners]

I had it with a dimmer switch where it worked off the wall but didn't when screwed back. Worked out that the angle of the cables going into the terminals meant it pulled the back half of the module away from the front and stopped it doing the biz when screwed back. Doesn't sound like your problem but I thought it was interesting!

 

[Zerax]

I'm had similar with the unit being crushed... as soon as you put a deeper back box in... problem goes away.

 

[pc1966]

Those shallow back-boxes are simply a pain, barely tolerable with a slim simple switch but unusable in practice with anything more complicated.

 

[Lucien Nunes]

Often due to pressure on the back of the accessory or tension on the terminals if the cables aren't ideally dressed and back box depth is limited. Form them into gentle flat curves from entry point to terminal, making sure there are the minimum possible number of crossovers. Once dressed, it should be possible to hold the accessory in its final position with light pressure from one finger. If you have to force it home harder than this you can run into this kind of problem, and also damage the cable insulation.

The accessory itself could also be faulty. If it is a fused connection unit feeding an appliance, I would not be completely happy to trust it now even if you can get the cables nicely arranged. If whatever was breaking contact is now making poor contact, it might work but overheat.