Re: Lighting circuits on a ring?

In post: bh01d1$s14ah$ snipped-for-privacy@ID-122774.news.uni-berlin.de,

Yes, they usually are. I'm not sure if radial circuits are okay for lighting, a better man than me will answer that.
Cheers Tim
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Hi Dave, Lighting circuits are normally run as radials - the 10m of cable saved per house means we get to wire 1 in 100 for free!! (nothing to stop you running them in a ring if you like tho')
Richard.
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Thanks everyone.
As far as I know the circuits I have seen have been radials.
However the reasons for running power in a ring might be equally valid for lighting. This thought prompted by previous thread about how many lights you could have per circuit.
I assume with a ring you could have more lights, in the same way as a power ring can have a higher rating in the consumer unit that a power radial.
About to split off one set of lights onto a new circuit and doing it as a ring seems as easy as doing a radial (just run two wires up to the loft together).
Cheers Dave R
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They're not. Lighting loads are known and fixed and tiny compared with what you find on a ring circuit, and the cable is grossly overrated anyway with 5/6A protection, so there's no point at all.

No, because some parts of the regs which allow for use of ring circuits apply only to 30/32A protected circuits. As far as the regs are concerned, you could use a ring, but not in order to derate the cable as is done on 30/32A ring circuits.

It is likely to confuse someone later and there's no advantage, so you shouldn't do it.
--
Andrew Gabriel

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David W.E. Roberts wrote:

They normally are not.
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In post: bh01p8$1v98$ snipped-for-privacy@custnews.inweb.co.uk, I said:

Apologies for this answer, I bow to everyone else's supperior knowledge!
Tim
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No. It would be a pain to wire for no gain. The cable used is quite capable of drawing so much extra power over the MCB rating that there would be no advantage. You want to keep the MCB rating down as some switches and light fittings require to be protected for 6A.
Christian.
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Hello David

"Should"? No.
"Can" Yes.
Either ring or radial, it depends mostly on the load expected. Not many would require more power than a radial, either 1.0 or 2.5mm, can supply. No point putting in a ring unless you do need more power since it uses almost twice the wire - /although/ some layouts might actually make it more economical to install.
If you've got one in and are wondering if it's right, just don't worry; whichever it is.
--
Simon Avery, Dartmoor, UK
uk.d-i-y FAQ: http://www.diyfaq.org.uk /
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David W.E. Roberts wrote:

No, not realy. since the cables are well able to cope with teh normal 6A circuit fuysing.
The p[oint about a ring is that it allows you to have a rednuidant path back to teh box, that giuves you both a safer earth (it goes two ways) and hopefully a slightly better current distribution in the cables.
Neither of which are so relevant on lighting.

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