Problems with fused spur backbox

[HenryGregory]

Hi there,
Having real difficulty getting through the knockthroughs on this backbox in a new build.
I am trying to install some cable for an intruder alarm control box. Wanted to run the cable for it behind the plasterboard where possible so it can't be tampered with.

I have a fused spur as pictured which is labeled security alarm on the consumer. Just can't get the backbox off of the wall, don't seem able to break a knockthrough off, starting to make a right mess of the plaster. Any ideas?

If not, I might have to get a different front plate with a hole for a power cable.
Any ideas or suggestions would be appreciated...

 

[JohnD]

I can't see any retaining screws. Is there one? If you undo any screws and run a craft knife round the outside edges of the box, that will release it from the plaster so you can pull it out.

The bodger who fitted it appears to have omitted a grommet.

 

[HenryGregory]

I can't see any retaining screws. Is there one? If you undo any screws and run a craft knife round the outside edges of the box, that will release it from the plaster so you can pull it out.

The bodger who fitted it appears to have omitted a grommet.

Yes there were two, have taken them both off. Have tried with knives, screwdrivers, not budging. Running an electrical cable / stud detector across the wall is suggesting it is smack bang where a stud would be.

 

[HenryGregory]

I have managed to use a hammer and screwdriver to get one of the knockthroughs off and it looks as though it is thick plasterboard the same thickness as the depth of the backbox. There is then breezeblock behind backbox so my plan is not going to work. Going to have to get one of these and run some flex. Very annoying..

Do you know what the rubber gromets are called and I will see if I can get some fitted whilst I am doing this.

Also, any suggestions on the best stuff to use to repair the mess to the plasterboard?
Thanks in advance

 

[JohnD]

Do you know what the rubber gromets are called

They're actually made of plastic, but they're called grommets. Yours will be 20mm.

DIY sheds will sell you a pack of ten for about the same price as an electrical business sells a hundred.
https://www.tlc-direct.co.uk/tcl/search?query=grommets&Submit=Search

It is pretty well impossible to fit one when a cable is in the hole, unless you slit it, which you're not supposed to do

MK and others make an FCU where the Load flex comes out through the bottom. There is a removable plastic plug. It looks neat.
https://www.tlc-direct.co.uk/Products/MKK0337.html

Filler and a metal filling knife will repair your plaster. Press very hard to get it flat and shave off any excess before it sets. I actually use finish plaster which I prefer, but the bags are bigger and it doesn't keep long in storage.

Have another go at slitting the plaster round the box. The knife doesn't need to be sharp, a decorater's scraper will do it.

 

[HenryGregory]

They're actually made of plastic, but they're called grommets. Yours will be 20mm.

DIY sheds will sell you a pack of ten for about the same price as an electrical business sells a hundred.
https://www.tlc-direct.co.uk/tcl/search?query=grommets&Submit=Search

It is pretty well impossible to fit one when a cable is in the hole, unless you slit it, which you're not supposed to do

MK and others make an FCU where the Load flex comes out through the bottom. There is a removable plastic plug. It looks neat.
https://www.tlc-direct.co.uk/Products/MKK0337.html

Filler and a metal filling knife will repair your plaster. Press very hard to get it flat and shave off any excess before it sets. I actually use finish plaster which I prefer, but the bags are bigger and it doesn't keep long in storage.

Have another go at slitting the plaster round the box. The knife doesn't need to be sharp, a decorater's scraper will do it.

Thanks very much, really appreciate that.
Have tried with everything I have and it is not budging. They have got it in there so tight it is unbelievable.

 

[dannyboi2003]

I think you've over complicated things, just run some surface trunking from the spur up to your alarm panel, all someone would have to do if they wanted to kill the power is pull the fuse out of the spur anyway, or pull the main fuse for the property if your electricity meter is external. Your alarm panel will have a backup battery so it will cope just fine with a power outage.

 

[AndyPRK]

This is how I remove knock outs.

Drill a hole into the middle of the knock out with a 7mm drill or similar size.

Then use a flat blades screw driver in the hole to lever the knock out out.

Anything else ends up disforming the back box

 

[RF Lighting]

Screw a tek screw part way into the knockout you want to remove and then wiggle it until the knockout comes away.

 

[HenryGregory]

Thanks for all of the advice guys. Try as I might, the back box was not coming out. I don't know what they had done, but it was just tearing the plaster board apart trying to get it off. Have taken several other back boxes off in the house, with no issue at all.

Here is the final result, I couldn't wait for a non-switched spur so went for this for now. Will change to a non-switched when I get time, but as a few already mentioned, the fuse box is actually located in the same cupboard so an intruder could just flick the security alarm switch in the consumer unit anyway! It has a backup battery so should be fine.

Thanks for all of your help on this!

 

[Sureitsoff?]

I know others might frown upon it but if you turn the FCU upside down you will then only have a tiny bit of cable showing

 

[JohnW2]

I know others might frown upon it but if you turn the FCU upside down you will then only have a tiny bit of cable showing

With a bit of judicious surgery (to the top 'edge'), one could probably achieve the same without having to turn it upside down.

Having said that, once the OP has changed it to an unswitched FCU, I don't think that even those "others" could really get very excited about 'which way up' it was installed!

Kind Regards, John

 

[AndyPRK]

and no issue if it was non switched