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')
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
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
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.
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.
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 /
No, not realy. since the cables are well able to cope with teh normal 6A
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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