On 2013-11-27, ARW wrote:

"Adam Funk" wrote in message
...
On 2013-11-27, John Rumm wrote:

So arguably with a ring with a B32 MCB that has two 2.5mm^2 ends, you
would mathematically arrive at 5mm^2 (hence 6mm^2 in practice), however
a 4mm^2 would be acceptable since we know that it can take the full 32A
load.

Does that apply outside the CU too, though? Would it be acceptable to
run a 4 mm^2 cable from a CU up to a junction box upstairs (let's say
it's a good one with Wago lever blocks in it) & then make a ring of
sockets with 2.5 mm^2 starting & ending at the junction box?


As John said, it's not a standard circuit. Appendix 15 of the 17th edition
is only a serving suggestion and not a reg.

The junction box in this case should be accessible for testing purposes.

I only mentioned the details of the box to avoid the idea of using a
round lighting junction box with various cable sizes jammed into the
screw terminals. ;-)

Dont worry: I'm not planning to do this --- I was just curious. In
practical terms, I doubt that running a 4 mm^2 T&E cable from A to B
would be significantly easier than running two parallel 2.5 mm^2
cables the same way.