Routing cable through a back box

[mrscalex]

I'd like to have 2 sockets (switched from a grid switch) vertically aligned with each other, maybe a couple of feet apart.

Is it safe and within regs to run the cable of the upper one through the metal back box of the first? In one instance the first box reached would be the cooker plate with 6mm cable.

Also, can I safely run 2x (or more?) 2.5mm T&E cables through a 20mm or 25mm metal conduit? Or even a 6mm cooker cable and a 2.5mm?

Thanks,

Robert

 

[ban-all-sheds]

Is it safe and within regs to run the cable of the upper one through the metal back box of the first? In one instance the first box reached would be the cooker plate with 6mm cable.

Can't answer that.

Also, can I safely run 2x (or more?) 2.5mm T&E cables through a 20mm or 25mm metal conduit? Or even a 6mm cooker cable and a 2.5mm?

But I can point you at the answer to this: http://www.tlc-direct.co.uk/Book/4.5.3.htm

 

[mrscalex]

Wow, those tables certainly suggest you can pack a lot in there. Way beyond what I even thought was physically possible, eg 8 x 1mm²,4 x 2.5mm² and 2 x 6 mm² in a 20mm conduit??

Good shout anyway - thanks.

BTW Is that 'can't' on the routing question because you don't know or a diplomatic way of telling me it's stupid to even ask!!

Regards,

Robert

 

[ban-all-sheds]

Wow, those tables certainly suggest you can pack a lot in there. Way beyond what I even thought was physically possible, eg 8 x 1mm²,4 x 2.5mm² and 2 x 6 mm² in a 20mm conduit??

Don't forget those examples are for singles - it's not saying you can get 14 T/E cables of those sizes in 20mm conduit! Total csa of that many singles is probably about 120mm², and the csa of 20mm conduit is approx 300mm²....

BTW Is that 'can't' on the routing question because you don't know or a diplomatic way of telling me it's stupid to even ask!!

It's because I really don't know.

 

[mrscalex]

Just found this thread which suggests going through a box is okay:

//www.diynot.com/forums/viewtopic.php?t=11591&highlight=pass

I get the impression it's a bit of bodge mind you.

regarding those tables. So how do I translate from single core to T&E as the outer sheath must be accounted for.

 

[ban-all-sheds]

If you think about it, the cross-section of T/E is more-or-less a rectangle with 2 semi-circles at each end. Given the major and minor dimensions of the cable (see the details of each cable on TLC's website), it's a fairly trivial bit of maths to work out the area

[code:1]
T/E Major Minor csa
1 7.80 4.25 29.3
1.5 8.20 5.00 35.6
2.5 10.30 6.00 54.1
4 11.90 6.25 66.0
6 13.50 7.00 84.0
10 17.10 10.00 149.5
16 19.40 10.00 172.5
[/code:1]