32mm hole in stud 4 x 2

robbie77 · 28 Jun 2020

Hi

I have agreed with my electrician to run some cables around for him. Part of the run involves drilling through joists which I don't have a problem with as have LABC guidelines/ regs of where I can drill but to get to the joist I have to drill some stud wall timber ( non load bearing) can I drill through a 4 x 2 with this size? The other route would be 2 x 22mm holes but I'd rather just do the one if possible?
I did a test piece hole and looked fine i kept it away from edges.
Thanks

DetlefSchmitz · 28 Jun 2020

It's probably fine. But to be honest it sounds like an excessively large hole to run a cable through, even at 22mm. It must be an enormous cable. Common sense says make the holes as small as possible.

robbie77 · 28 Jun 2020

Well it's a 10mm for shower, two 2.5 for ring and light cable. Come to think of it I might just need that size for when the shower terminate for the isolation and then runs to the shower.
Electrician said keep the wires together as much as possible.

DetlefSchmitz · 28 Jun 2020

I would have thought 22mm would take the lot anyway. Take a piece of spare wood, and drill the hole. Then poke the wires in question through and see if it's a problem. I don't think it will be.

Taylortwocities · 28 Jun 2020

32mm is structurally too big.

Max hole size allowed is 0.25 x joist depth.
4" = 101mm so your biggest hole size is 25mm
Drill two smaller holes a suitable distance apart (NOT LESS than 3 x hole size)
Distance etc are all given here
http://www.elecsa.co.uk/Documents/Contractor-Documents/Pocket-Guides/Pocket-Guide-20.aspx

DetlefSchmitz · 28 Jun 2020

Taylortwocities said:
32mm is structurally too big.
...
http://www.elecsa.co.uk/Documents/Contractor-Documents/Pocket-Guides/Pocket-Guide-20.aspx

Note that, as far as I could read, we're talking about studs, not joists.

EFLImpudence · 28 Jun 2020

robbie77 said:
two 2.5 for ring and light cable.

Does that mean two 2.5 for ring PLUS light cable, or you are using 2.5 for light cable.

If you are running both legs of the ring in the same place, then you might not be doing it the best way.

Taylortwocities · 28 Jun 2020

DetlefSchmitz said:
Note that, as far as I could read, we're talking about studs, not joists.

Ah, yes. Probably OK for non load bearing stud -although- I have found that if you have too many separate cables through a constricting hole that there's a danger of chafing as the later cables are added.
I'd still put in two holes. dont think you'd get a 10mm+2x2.5+a 1mm through a single 32mm hole anyways.

Probably the best check is

DetlefSchmitz said:
Take a piece of spare wood, and drill the hole. Then poke the wires in question through and see if it's a problem.

Notch7 · 28 Jun 2020

DetlefSchmitz said:
Take a piece of spare wood, and drill the hole. Then poke the wires in question through and see if it's a problem.

yes Ive done that few times - it take a minute and saves a lot of swearing later (DAMHIK)

bernardgreen · 28 Jun 2020

robbie77 said:
Electrician said keep the wires together as much as possible.

Bunching cables reduces the maximum acceptable current in the cables.

A couple of smaller holes spaced as per building regs is better.

That said in walls bunching may be necessary to comply with keeping all cables in the "safe zones"

robbie77 · 28 Jun 2020

DetlefSchmitz said:
I would have thought 22mm would take the lot anyway. Take a piece of spare wood, and drill the hole. Then poke the wires in question through and see if it's a problem. I don't think it will be.

Yeah I tried that. I can get 1 x 10mm and 1x 2.5mm max!

robbie77 · 28 Jun 2020

EFLImpudence said:
Does that mean two 2.5 for ring PLUS light cable, or you are using 2.5 for light cable.

If you are running both legs of the ring in the same place, then you might not be doing it the best way.

No sorry that's my fault you are right the leg for the return is the other side of building. It's 1 x 2.5mm, 1 x 10mm and 1 x 1.5 or 1mm for lights.

robbie77 · 28 Jun 2020

Taylortwocities said:
32mm is structurally too big.

Max hole size allowed is 0.25 x joist depth.
4" = 101mm so your biggest hole size is 25mm
Drill two smaller holes a suitable distance apart (NOT LESS than 3 x hole size)
Distance etc are all given here
http://www.elecsa.co.uk/Documents/Contractor-Documents/Pocket-Guides/Pocket-Guide-20.aspx

Joists are 8 inch so I think the hole for these is OK it's the non load bearing stud work that's 4 x 2. Maybe do 2 smaller through these?

robbie77 · 28 Jun 2020

DetlefSchmitz said:
Note that, as far as I could read, we're talking about studs, not joists.

Yes

DetlefSchmitz · 28 Jun 2020

Two smaller much better.

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32mm hole in stud 4 x 2

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