After spending the last year building an extension I now find that I cannot simply extend the groundfloor ring circuit as this also incorporates the upstairs ring circuit. This area conveniently measures 98 sq.m.
So a separate circuit is required. Of course the CU is on the opposite side of the house. Running cable under the floorboards is impracticable so here is my question.......
Is it acceptable to run 5m length T&E up the side of my house (into the loft) if it forms part of the ring circuit?
I don't completely follow what you are suggesting.
Basically you want to run a separate circuit for the extension, so the existing one is not really relevant to that, except that you are saying that since it covers near to the maximum area you wouldn't extend it.
For the new circuit, you could run it as a ring circuit, and it is perfectly reasonable to run the two cables required through some other space using the normal rules of running cables - i.e. within 150mm of corners or tops of walls etc. unless protected and grouping rules. They can be run together until you reach the area and then go off in different directions as you form the ring, or even run physically but not electrically in parallel as long as a ring electrical layout is achieved.
When you say "run up the side of my house (into the loft)", if you mean run outside the building in PVC T&E then the answer is no, it is not suitable for outdoor use because UV from the sun breaks it down eventually. It should be run inside the house.
An alternative, if the load is not expected to be significant, is to run the circuit as a radial one using 2.5mm^2 T&E and a 20A breaker or
4mm^2 with a 32A one. However, since cable is cheap and you are going to have to run one cable, you might as well run two, so I am not sure that it makes sense to do this.
Thanks for the reply. Sorry if my English was not clearly understood.
My house has a floor area of 96 sq.m. supplied from just one ring circuit. So, as I understand, I am not allowed to go above 100 sq.m. Hence the need for a new ring from the CU in the kitchen.
The easiest way to provide the power (20A and 6A, via new CU with extra space for the mcb's) would be to run the cable through the kitchen wall, up the outside of the house, across the loft, then into the new extension.
The cable (2 x 2.5mm + 1 x 1.5mm) would be in 25mm conduit attatched to the outside wall. Facing N.E.-ish, this wall receives virtually no direct sunlight.
Is this allowed or do ring circuits have to be completely indoors?
Def-nit-lee a better idea, as Ed says. For us d-i-y'ers, HiTuf/SuperTuf is easier to work with than SWA - it's a circular PVC cable with a harder and UV-resistant outer sheath, and goes into CU boxes through simple compression glands. CPC sell cut lengths by mail order, as will most electrical counters (watch for the break-even point between buying a cut length and a 50m roll).
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