How many cables in one backbox?

[GaryMo]

I can get 56 (maybe 57) in a single plate 4 gang 2 way switch (though I'm pretty sure 3g is the largest for single plate)....

4 seperate circuits, each having an incoming t&e.
4 outgoing t&e (SW&N) to each luminaire.
4 outgoing 3c&e (2 way switching).
4 outgoing 3c&e to fans.

Excessive? Hell yeah!

40 live conductors.
16 CPC's (maybe 17 if you count a flying earth to the backbox).
A total of 56 (maybe 57) conductors.

Or 42 (maybe 43) if 3 gang 2 way.

 

[ban-all-sheds]

4 outgoing 3c&e to fans.

No - only 1 switched live per gang to leave the box - I meant, more accurately, only one cable per gang out to a light, i.e. no "cheating" by assuming that each gang has multiple cables leaving to multiple lights. Or fans.

In fact, for every fan with a permanent live requirement you can add 1 more conductor, so if all 3 (or 4?) switches control a fan that makes 42 (or 56?) conductors.

But even with just 1 cable going off to a light, per gang, it's still 39 (or 42?).

Plus 1 for the fly-lead - I'd forgotten that.

Excessive? Hell yeah!

It would be a bit of a squeeze. You might want to set your 47mm box a bit further back into the wall.....

 

[LoveRocket]

Hmmmm, very interesting. But anyway, back to the OP, would it be practicable to have the loop in/out and one switchplate, and the feeds to the lamps at the other? That way you're down to 4 cables in each. Or maybe use one 3+E to the first light (carrying both swLs and an N) to the first light, then a T+E to the second?

 

[Chri5]

It would be a bit of a squeeze. You might want to set your 47mm box a bit further back into the wall.....

And break the rules for building regs (approved doc A) regarding depth of chase in a wall leaf ?

 

[ban-all-sheds]

Ah.

Excessive? Hell yeah!

It would be a bit of a squeeze. You might want to build a thicker wall.....

 

[LoveRocket]

It would be a bit of a squeeze. You might want to set your 47mm box a bit further back into the wall.....

And break the rules for building regs (approved doc A) regarding depth of chase in a wall leaf ?

Doesn't that relate to the depth of the chases, rather than the hackouts for backboxes? It's more to stop people removing half their wall as they chase horizontally for 20ft.