methods of running cables

[neilyboy]

I have been asked to fit some new sockets and lights in a room on the external wall,the wall is insulated with kingspan and there is no gaps between any framing or the kingspan.
There are no other sockets/switches on this wall.I can get above the room and limited access at floor level if I lift the chipboard.
My question is how do I get the cables down/up the walls ?

 

[brianmoooore]

There should be a gap behind the insulation.

 

[neilyboy]

There should be a gap behind the insulation.

No,nothing,I cut a socket size piece of plasterboard out its a kingspan sheet with another sheet behind it total depth is probably 100mm ish with the back sheet hard against the osb sheet used to form the wall

 

[littlespark]

Looks like a job for a piece of 16mm pvc trunking lid.

I can’t see this happening without more holes being cut.


I have, once, drilled right through an upstairs socket box to outside, black pvc conduit and end boxes vertically, then drilled back into a be socket. (Was close to a black pvc down pipe)
But that was solid block walls and they didn’t want their decoration disturbed.

 

[DefyG]

If no gap per #2 (there should be air gap I would have thought for ventilation), treat it like any other solid wall.

 

[neilyboy]

If no gap per #2 (there should be air gap I would have thought for ventilation), treat it like any other solid wall.

yes had thought about this but explaining that to the householders is very..difficult

Looks like a job for a piece of 16mm pvc trunking lid.

I can’t see this happening without more holes being cut.


I have, once, drilled right through an upstairs socket box to outside, black pvc conduit and end boxes vertically, then drilled back into a be socket. (Was close to a black pvc down pipe)
But that was solid block walls and they didn’t want their decoration disturbed.

that is thinking outside of the box ...

 

[brianmoooore]

If no gap per #2 (there should be air gap I would have thought for ventilation), treat it like any other solid wall.

The reference to OSB makes me think this is a might be a modern timber frame (dolls') house. There should be a 50mm cavity the other side of the OSB.
In my first post I was assuming a solid wall that had been retrospectively insulated - something I'm much more familiar with.

 

[DefyG]

The reference to OSB makes me think this is a might be a modern timber frame (dolls') house. There should be a 50mm cavity the other side of the OSB.
In my first post I was assuming a solid wall that had been retrospectively insulated - something I'm much more familiar with.

The wrong side of a vapour barrier?

 

[brianmoooore]

VP should be right behind the plasterboard, with a breathable membrane the other side of the OSB.
Some sparkies, with less than ideal scruples, might be tempted to fish a cable down the cavity.

 

[Pretty Mouth]

VP should be right behind the plasterboard, with a breathable membrane the other side of the OSB.
Some sparkies, with less than ideal scruples, might be tempted to fish a cable down the cavity.

Would this be the cavity between breather membrane and outer leaf? (whether that be that brick/block, or cladding, etc) Have to admit, this is one of the ways I'd be considering doing it.

Another way could be to cut out a wide-ish strip of plasterboard following the cable route, then remove a narrower strip of the insulation along the middle of it. Cable goes in the groove in the insulation, then glue the strip of plasterboard back in place over the top. I think a polyurethane glue such as gorilla glue is necessary for this.

 

[brianmoooore]

Any method that places the cable in contact with the insulation will cause it to be derated of course, so that will need to be taken into account.
It's a bit naughty running the cable down the cavity, but as long as you aren't too concerned about things like maximum spacing of cable fixings (there won't be any), and can keep the cable fairly taught to keep it away from the outer leaf, there shouldn't be any problems.

 

[Mike Johnson]

Do it the right way chase down the face of the wall and instal a conduit, making good afterwards may require another trade if you aren't up to it.

@brianmoooore Dolls house love it.