Hole in joist (different query) - 2.5mm T&E

Jun 26, 2019 Last reply: 7 years ago 4 Replies

I'm just getting back into the DIY mind set and rooting around in the shed to dig stuff out of my stash.



I'm extending the 13A ring in the 3rd bedroom/office, and need to run two



2.5mm T&E wires through the joists. Ring out, and ring return.

I've put my digital callipers on the T&E and it is perhaps a whisker under



10mm wide.

I assume that a 10mm hole would be just adequate to pass a single wire.



However I do have a 16mm spade wood drill as well.



Would it be acceptable/better to drill a single 16mm hole and run both wires?



Cheers


Dave R


That's what I've done - and in some cases 20mm with two, plus a couple of lighting wires.

Yes they are all together and that affects how much heat they can lose to the air, but it is only for a very short distance and copper conducts heat very well, so local overheating is very unlikely, as it'll travel along and escape elsewhere.

SteveW

Depending on how many joists and how much cable you have to pass through the joists is the deciding factor. I would suggest buying a new 20mm or even a 25mm spade bit.

IME its not worth messing about with holes that are "just big enough" and "in theory" - just slap a 20 or 25mm bit hole in the joist and make life nice and easy for threading stuff through and pulling in cable.

Larger bit now being searched for in stash. :-)

Thanks to all who responded.

Cheers

Dave R

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