DUAL flush boxes

[daytona]

that gap doesnt sound big enough to me.

 

[ban-all-sheds]

BAN,are you sure you can get a good enough bend radius on the cableto turn it in?

No.

Nor am I sure I can't.

them knockouts in the center (the whole bit) do pop out fairly easy,i can see it getting a bit mashed.cant you use a back or side entry on the box and just run the cores through the center knockout?
i think thats a bettewr job and no pressure on the steel wire

Yup - that's another method I thought of - I'd have to hack a bit more of the wall away to accommodate the back of the gland, but it wouldn't be an impossibility.

 

[RF Lighting]

What about using a twin and a single box attatched with 20mm bushes and couplings, but leave out the bush from the top coupling in the twin box.

This will leave an ideal place to screw a BW20s gland into.

Using a twin box will allow a little more room for your bend radius, and earthing the back boxes will also earth the armouring too

 

[daytona]

just drill a 25mm hole through the wall and back entry it.that should take a bw20s ok(with a wiggle on the drill bit).

 

[ban-all-sheds]

I guess it will, won't it.

And I could fill the rest of the hole around the cable with silicone...

RF - what's the bottom coupling for?

 

[RF Lighting]

Just for a bit of stability. Those boxes are not especially rigid.


You could omit it if you like.

 

[daytona]

i meant drill a 20mm hole through the wall and just two inches or so with the 25mm to take the gland.

so i guess thats what i should have said then.....

 

[RF Lighting]

25mm to take the gland.

Fnarr fnarr

(sorry)

 

[ban-all-sheds]

Just for a bit of stability. Those boxes are not especially rigid.


You could omit it if you like.

OK.

They'd be screwed to the wall and plastered in anyway.

 

[ban-all-sheds]

i meant drill a 20mm hole through the wall and just two inches or so with the 25mm to take the gland.

so i guess thats what i should have said then.....

And I guess I should have used a as I wouldn't really drill a 25mm right through.

Mind you - regarding the wiggle on the drill bit - the only 25mm I've got is 1m long, so the chances of not wiggling it a bit as I try to enlarge a couple of inches are smaller than a small thing that's very small. Maybe a small cold chisel and a little more time taken would be better. Or sacrifice a cheap holesaw.

 

[Lectrician]

You want to gland into the divider? Am I reading that correctly? That will never work

Tell me more - may save me the the job of finding that out for myself.

It'd be a 20S gland - the width across the flats is 24mm and across the points is 27mm, so right now no immediately obvious reason why it wouldn't go in a 35mm box. Being internal there'd be no need for the "dog's ****", and I wasn't so sure that I couldn't bend 2.5mm 3-core within the space that I thought it wasn't worth further investigation....

you would not be able to form the cable into a bend in that tight space, and even if you did manage to do it, it would not comply with the bending radius for the cable.

The deviding fillet in most boxes is also only 'loose' between a couple raised tags. I know some are fixed, but even then they are flimsy and would be deformed when you try to form the cable.




RF's method does not give much more space either to be honest.



I would enter into a bottom knockout, and plaster it in. Use a 35mm box, because this sets the 20mm knockout further back. Use a 20mm brass bush and serrated washer to bush a 20mm galvanised conduit coupler to the box. Then gland into the coupler. This leaves plenty of space in the back box, and you can simply use a single box.

Either that, or use some 4mm split concentric, and treat it as T+E inside - grommet it. Duct it where burried, TRS gland into sockets/enclosured outside.