Getting Downstairs - Cable Runs

[Barney12]

Hi All

 

I'm pondering how I get my cable runs (lighting and power) from 1st floor to ground floor. Particularity the lighting runs which are in large part on vaulted areas. In a "normal" house you have the ability to run your cables clipped down the roof trusses but with a fully insulated frame thats a no go. Plus the counter battens make it trickier still. As we are running radial circuits for lighting and power I've got a fair few runs to get to the ground floor. I'm thinking I'm going to have to come down the walls at strategic points but how does that work with safe zones?

 

I'd be interested to know what others have done?

 

A few pics in illustration:

 

[Jeremy Harris]

Come down the walls, with the cables clipped as far back as you can get them to the sides of the counterbattens.  That's what we did and it worked pretty well.

[Barney12]

1 minute ago, JSHarris said:

Come down the walls, with the cables clipped as far back as you can get them to the sides of the counterbattens.  That's what we did and it worked pretty well.

 

That was my first thought but then started thinking about safe zones for cable runs?

[ProDave]

Safe Zones are your answer. Basically straight up,. down, left or right from any accessory, and 150mm from the wall / ceiling joint.

 

Assuming a sloping ceiling is still a ceiling, then anywhere, so that bit is easy.

 

To get from first floor void to downstairs, any safe zone created by any accessory, and of course the consumer unit creates a safe zone above it, so first floor wiring staright up from CU to floor void above.

 

Nothing wrong will drilling a counter batten to run cables through in a safe zone. I like to make my life simple so when fitting vertical battens for a service void, I leave a small gap at socket and switch height to save having to drill them.

[MikeSharp01]

Had a similar issue last week the safe zones give you plenty of room to play with along the walls. If you must protect (IE no Earth leakage trip) then run 20mm conduit in the service void.

[Jeremy Harris]

I arranged all our sockets and switches to be adjacent to counter battens, so all the runs were in safe vertical zones.  My thinking was that someone was far more likely to either drill into a counter batten to fix something, or into a clear bit of plasterboard to fit an expanding plasterboard fixing, so by keeping all the cables along the side of the battens, well to the rear, it minimised the risk of someone drilling through a cable.  I also took lots and lots of photos, showing all the cable and pipe runs, before the walls and ceilings were boarded out, and they have proved invaluable since.

Edited August 29, 2017 by JSHarris

[ToughButterCup]

13 hours ago, JSHarris said:

I arranged all our sockets and switches to be adjacent to counter battens,

 

For those of us who, like me, have no idea what a counter batten might be,  have a look at this

[Onoff]

I'm a big fan of treating left/right, up/down from an accessory as sacrosanct, no go areas for the length of the walls. You could:

 

- Run the lighting feed(s) vertically up BEHIND a back box say a light switch. Might be awkward but very doable. 

 

- Run the lighting feed(s) vertically up WITHIN a back box. Some consider it bad practice especially if it's say a lighting feeding running up thru a back box on the ring. Personally I can't see an issue. Don't forget your grommets. Keep it to the back corner and write on it "LIGHTING" with a Sharpie. Deeper boxes like 47mm give you more room to manoeuvre. You could even re-drill with a 20mm Starrett and slip in a bit of conduit where it passes thru the box again depth/accessory dependent.

 

Either way all cabling's kept within the safe zone.

[Jeremy Harris]

The problem with absolutely vertical runs over the dead centre of a box with the MBC system is that you really have to fix the cables to the counter battens - the green board in the photos is the vapour barrier.  What I did was glue and screw thin ply spacers to the green board adjacent to counter battens (so that the 45mm deep back boxes protruded slightly into the plasterboard, with no gap).  The boxes were then screwed (with sealant) to these spacers, tight against the edge of a counter batten, and the cables run out of the nearest top knockout to the batten and run vertically up the wall to the floor or ceiling void above. 

 

There's a slight offset from being dead vertical over the centre of each box, but all the cables do run within the vertical zone delineated by the box edges, so are OK in terms of the regs.  I opted to not have any horizontal runs in walls anywhere, but run everything up and down to switches and sockets.   The only exception to this was the speaker wiring in the living room, where I did drill through the counter battens and run it around the room.

Edited August 30, 2017 by JSHarris

[Nickfromwales]

The difficult part is trusting the sparky to drill next to the airtight membrane WITHOUT damaging it, or worse, not telling you that they've damaged it . For the vaulted ceilings, I think I'd counter batten ( 100mmx25mm ) over the counter battens and use the first set for clipping to, thus removing the need to drill them. That would also mean you'll never be able to screw through a cable whilst doing the overhead boarding. I'd also counter batten the OSB'd wall unless there's a route behind it / you don't need to get cables up that elevation. Those could be just marginally bigger than doorstops, spaced to take the plasterboard accordingly.  

Edited August 30, 2017 by Nickfromwales

[Jeremy Harris]

That's one reason that I drilled most of the holes and fitted all the noggins etc in place.  I'd only have myself to blame if I screwed something up!

[ProDave]

Knowing how poor most tradesmen are in regards to insulted and sealed houses, I would concur that you either need to give them a good briefing, and supply them a roll of airtightness tape to fix any punctures, or do all the drilling yourself.

[Barney12]

59 minutes ago, JSHarris said:

That's one reason that I drilled most of the holes and fitted all the noggins etc in place.  I'd only have myself to blame if I screwed something up!

 

I'm doing the majority of the first fix. I prefer it that way as I'll be sure its right and my sockets/outlets are where I want them!

[Barney12]

1 hour ago, JSHarris said:

The problem with absolutely vertical runs over the dead centre of a box with the MBC system is that you really have to fix the cables to the counter battens - the green board in the photos is the vapour barrier.  What I did was glue and screw thin ply spacers to the green board adjacent to counter battens (so that the 45mm deep back boxes protruded slightly into the plasterboard, with no gap).  The boxes were then screwed (with sealant) to these spacers, tight against the edge of a counter batten, and the cables run out of the nearest top knockout to the batten and run vertically up the wall to the floor or ceiling void above. 

 

There's a slight offset from being dead vertical over the centre of each box, but all the cables do run within the vertical zone delineated by the box edges, so are OK in terms of the regs.  I opted to not have any horizontal runs in walls anywhere, but run everything up and down to switches and sockets.   The only exception to this was the speaker wiring in the living room, where I did drill through the counter battens and run it around the room.

 

My service battens are only 38mm deep. Thus I was thinking about just screwing a 45mm back box straight to the green board.?

 

I was thinking I might just split the batten with the Fein so that the socket is in the middle of the batten run and then cable clip to the batten. Would not be a huge amount of work.?

 

Edited August 30, 2017 by Barney12

[Triassic]

28 minutes ago, Barney12 said:

was thinking I might just split the batten with the Fein

 

If I were doing it I'd have to use the Aldi rather than the Fein !

[Jeremy Harris]

33 minutes ago, Barney12 said:

 

My service battens are only 38mm deep. Thus I was thinking about just screwing a 45mm back box straight to the green board.?

 

I was thinking I might just split the batten with the Fein so that the socket is in the middle of the batten run and then cable clip to the batten. Would not be a huge amount of work.?

 

 

My counter battens were 50mm deep, hence having to use a bit of ply packing to bring 45mm boxes out far enough to protrude into the plasterboard, with no risk of a gap.  With 38mm deep counter battens then  that's an ideal depth to fit 45mm deep boxes directly, with them protruding half way into the plasterboard.

 

What I did was use blobs of low expansion foaming glue (the Evostick stuff that cures in 5 minutes and comes in a gun cartridge) behind the boxes as sealant around the screw holes.  This worked well, as the boxes tended to stay in position whilst the first screw was being put in, which makes it easier to juggle the screw, driver, box and torpedo level when getting the boxes spot on.  The trick was to squirt a tiny bit of glue on the back of the box, wait a few seconds, then position it on the green board and wiggle it where you want it, getting it level as you go.  Push hard, and it should stay where it is, leaving your hands free to pick up a screw and the driver and start screwing it into place.  Hopefully, because the glue was around the screw holes on the back of each box, so the screw went through it, it helped to form a good vapour seal.

 

I'd not bother faffing around trying to cut sections out of counter battens unless you really have to, as the vapour tight coating on the green board isn't that thick and could easily get damaged.  Leading cables out through the nearest knock-out to a batten, and then clipping the cables tight up the rear edge worked well enough.

[Onoff]

28 minutes ago, Triassic said:

 

If I were doing it I'd have to use the Aldi rather than the Fein !

 

Cheap seats like me with my Parkside!

[Nickfromwales]

Makita baby. ?

[PeterW]

2 hours ago, JSHarris said:

That's one reason that I drilled most of the holes and fitted all the noggins etc in place.  I'd only have myself to blame if I screwed something up!

 

Likewise !!

 

Sparky doesn't know what to do with himself...!

[Stones]

23 hours ago, JSHarris said:

.  I also took lots and lots of photos, showing all the cable and pipe runs, before the walls and ceilings were boarded out, and they have proved invaluable since.

 

Same here, useful for remembering where pipework is located as well.

[Onoff]

I never take any photos...