Plasterer / Sparky question

[dicky113]

When plasterboard is attached to blockwork do you use shallow pattresses for electrical points or do you drill out the blockwork to sink standard sized ones?

How far does the finished plasterboard stand out from the wall once it has been attached?

[The Builder]

Hi Dicky.............if you mean standard metal back boxes..........then they are usually let in to the masonry so that they finish flush with the face of the plasterboard.........this lets the plasterer's trowel travel right across the box in one movement..............if you see what I mean :o)

[tezestwing]

Hi dick TE (tapered edge) plaster board is usually 12.5 mm thick with adhesive dabs it will be about 14/15 mm from blockwork 25mm box will then need approx 10mm chase hth Tez

[Disco Fever]

Whatever you do DON'T get the shallow boxes for socket outlets or when it comes to fitting the sockets you'll find they wont go back to the plaster and also if your fitting the flat plate type of metal socket fronts then you will need a 35mm deep box otherwise use a normal 25mm deep box....

[dicky113]

Thanks for all the answers so far. Tezestwing you say that the 12.5mm board will be about 15mm proud of the wall. Does this mean all the electrical wiring needs to be chased in to the blockwork? I assumed that it would be just hidden in the gap between the blockwork and the board. I guess it would need to have metal conduit of some sort then to prevent people banging picture hooks into it?

[tezestwing]

it is far easier to first fix the ceiling leave enough cable x2 for ring main for drop to socket outlet + trimming, then fix plasterboard all out, then chase vertical cable runs with sharp blade + straight edge through to block work down to socket location blade round socket, bolster out block fit and fix box flush to choice then just lay cable flat side by side into the chase then cover cable with plastic http://www.screwfix.com/prods/31046/Electrical /Conduit/PVC-Channel/PVC-Channel-1-Pack-of-25; jsessionid=Q0TQYT1DFPJSWCSTHZOCFEY then plaster out and skim hth Tez

[LCDMAN]

Never heard of the safe zones then? DON'T be stringing cable willy-nilly behind plasterboard, please, do some research and find out what is permissible under the 17th Edition IEE wiring regulations and Part P of the Building regulations. Or stop being a tight wad and call in a professional sparks (like me) who knows what he is doing. With all due respect , it sounds very much lke you don't.

[LCDMAN]

Any cables not buried AT LEAST 50mm will need RCD protection or to be contained in earthed metal conduit.

[dicky113]

LCDMAN

You say "call in a professional sparks (like me) who knows what he is doing. With all due respect , it sounds very much lke you don't. "

No, you are right I dont know. I thought that was what this site was all about. you don't know something, but want to, you ask a question and people reply.

By the way, who said I was going to do the work?

[LCDMAN]

Have a read here;

http://www.ultimatehandyman.co.uk/forum1/diy-e lectrical-work-and-the-law-t6296.html

It outlines what you can/can't do for yourself under the 17th Edition IEE wiring regs and Part P of the Building Regulations., especially concerning the new "Special Locations" (kitchens, bathrooms, outside etc.)

Sounds like you are doing amendments / modifications / provision of new circuits, so it will be notifiable work and must be carried out to 17th Edition. Who's going to be testing and certifying this work? Who is the "competent person" supervising this work? Have you notified your LABC?

[LCDMAN]

Knobby, need to have proper Insulation resistance test of that lighting circuit, to check for potential live/neutral/ or live/earth fault. Incandescent lamps are like the old wired fuses, they are a lot less "intrusive" in circuits and more "forgiving". Changing to an energy saver (basically a cold cathode fluorescent) will show up any long-standing faults.

[LCDMAN]

Hmmm........ try asking my fellow sparkies over here;

http://www.talk.electricianforum.co.uk/

[dicky113]

Knobby, you said "If your not going to do the work,then why ask? "

I asked because I am interested.

I got four good answers from people who understand this site and then a non-answer and off topic posts from you and Lcdman..... enough said.

Thanks to those who gave thoughtful replies though.

[LCDMAN]

Just because you didn't like my replies doesn't make them less valid! Part P and the 17th Edition IEE regs are there to stop those with no knowledge doing something stupid ("I assumed that it would be just hidden in the gap between the blockwork and the board.") and making things dangerous for themselves or others. It was obvious from your initial question that you have little or no knowledge in this area, and your subsequent answers suggested that you were potentially planning to do this work yourself.

The rules are there for everyone's safety and benefit - my advice still stands, either research them and follow them or get someone in who does and can.