T&E behind plasterboard

[monday]

What is best practice when running T&E behind existing dot and dab plasterboard?

I want to run a spur to an FCU from an existing double socket on a ring final. Plasterboards is on dabs over aerated concrete block, being the inner skin of a cavity wall. If I channel through the dabs, I reckon I can fish the cable through the hollow "non-dab" sections. I have about 1m to an internal corner, then another 1m along the adjacent wall. The FCU and the socket will be at the same (current standard) height above floor level. If I just re-plaster my "channels" the cable will be trapped - is that a problem or should I use capping to leave some limited mobility to the cable.

The socket and the rest of the electrics are part of a professional install in a ground floor extension only 18 months old [some serious lack of planning here!) so I don't want to screw it up with a bodge.

 

[Iggifer]

If you can do a neat enough job of cutting out the plasterboard, you can likely just use that to make good the holes again, and then just fill the gaps & skim, rather than trying to fill the holes entirely with plaster.

Keep your lines square and even if the plasterboard breaks when you pull it off the dot & dab, you can cut a new piece to suit.

No need for capping, just clip your cable to the block. You will absolutely not be able to pull the cable through capping with a 90° bend anyway, and capping is only to stop it getting damaged by a trowel, and if you do a good job of cutting the board, you won't need a trowel

 

[ban-all-sheds]

And even if he does the cable will be below trowel-swiping depth.


Bring back proper walls, I say.

 

[Lectrician]

Make your hole for the FCU. See how far you can slide some trunking lid behind the board. Mark this on wall and make a narrow hole. Stitch your cable this way to the socket. Fill the small holes you made.

 

[PrenticeBoyofDerry]

What you must do is keep the cable within the permitted cable zones and whilst pull cable through it should not cause any damage to cable.
Dot'n'Dabs can be quite randomly distributed, so you may encounter some along the route of the void and need to chase this area out.
If you cut whole for backbox and chase any areas that could compromise the integrity of the board fixing to wall, it is advised to apply some more wall adhesive in these areas to bond wall to board.
//www.diynot.com/wiki/Electrics:walls

I assume due to the age of the existing installation, that RCD protection is present?

 

[monday]

I assume due to the age of the existing installation, that RCD protection is present?

Yes, RCD protection on this circuit.

Thanks to all for suggestions and advice. I'll get digging. I find that tapping the wall (John Cleese-style) is a useful preliminary indication of dab locations. At least I know there is nothing else lurking under there since I was able to take pictures of the cabling at first fix stage before the plasterboard went on.