Conduit and Wall box depths

Closte · Posted: Mon Sep 13, 2004 3:52 pm Post Subject: Conduit and Wall box depths

Maybe this is a plastering question but....

I have a new outbuilding that is awaiting the plaster; leaving time for me to carry out the wiring.
My question is what trunking/conduit is best to use so that the there is enough depth to cover with plaster. Also what depth do I need to leave the plasterers to ensure the conduits etc are covered...?

How proud should the boxes be for the light switches, sockets etc

The wall is Breeze (Fen-Light) block with concrete floor.
Does anyone have a ny links on this particular area....

Thanks in advance...

dingbat · Posted: Mon Sep 13, 2004 4:15 pm Post Subject:

Use 'top hat' galvanised capping, fixed with galvanised nails or rust-proof screws directly over your cables. It comes in various widths and is available at any electrical wholesaler, or you can get it at most builders merchants and DIY sheds. Whether wet plaster or dot-and-dab this will be perfectly acceptable to the plasterer. (To do a really pucker job you should turn over the sharp cut ends of the capping)

Ask your plasterer about the depth for galvanised back boxes. If' he's dotting and dabbing he may be happy for you to fix 25mm deep boxes directly to the wall surface, but otherwise you should sink them to about half their depth. You should be able to leave 16mm light switch boxes at their full depth.

ban-all-sheds · Posted: Mon Sep 13, 2004 8:17 pm Post Subject:

Don't use 16mm light switch boxes.

The day someone wants to put a 2-gang intermediate in there, or a 2-gang dimmer they will curse you and your descendents unto all time.

__________________
I mustn't warn people that the "experts" on the plumbing forum can't be trusted to tell the truth.

securespark · Posted: Tue Sep 14, 2004 1:22 am Post Subject:

My worst nightmare was a three gang switch in a 16mm box, AND all of them were two way, with 5 conductors in each switch. ^&*(^$ knows how the guy did it. I had to admit defeat and tell the guy it needed a deeper box. All he said was "it was all right till you came...."

Well it wasn't cos the switching did not work properly.

Closte · Posted: Tue Sep 14, 2004 9:46 am Post Subject:

Thanks a lot for your answers on this one....

25mm Light boxes are the way then

Newspark · Posted: Tue Sep 14, 2004 10:47 am Post Subject:

Can someone tell me is capping a regulation or is it just good practice? I know you need it if the cable runs at an angle but do you need it if it runs straight and within 150mm of a corner or the ceiling??

dingbat · Posted: Tue Sep 14, 2004 10:59 am Post Subject:

Good practice. And outside the permitted zones capping is not adequate protection. Cables outside permitted zones ( http://www.tlc-direct.co.uk/Book/4.4.1.htm ) must be at least 50mm deep or mechanically protected against penetration by nails or screws.

ban-all-sheds · Posted: Wed Sep 15, 2004 7:28 pm Post Subject:

http://www.niceic.org.uk/approved/quest3.html

http://www.niceic.org.uk/downloads/C5-43.pdf

__________________
I mustn't warn people that the "experts" on the plumbing forum can't be trusted to tell the truth.