On Fri, 10 Oct 2003 19:50:42 +0100, "David Hearn"
wrote:


"David Hearn" wrote in message
...
I'm trying to add some sockets to a bedroom upstairs, and I'm in the
process
of working out how best to break into the ring and extend it by a socket
or
two. (We have 1 double socket in each of the two larger bedrooms and a
single socket in the small bedroom! What a waste of a 32A MCB)

snip

What I'm after really is an idea of the size of wiring I need to use to
extend the ring (I'm planning on just breaking into it at an existing
socket, and then taking one wire to a new socket, and then joining the two
sockets together to rejoin the ring).

This should be 2.5mm T&E.

However, looking at your picture, something appears to be wrong with
cable sizings.

The first position does appear to have the thickest cable - which it
should, but I can't easliy tell whether it is 4mm^2 or 6mm^2.
The second position appears to have 2.5mm T&E.

However, I am concerned about everything to the right of there - it
appears to use a small cable, possibly 1.5mm^2. Certainly this is
not enough for a 32A ring circuit, or even a 16A circuit.

Generally, the immersion heater, if there is one is run from a 16A
(blue) MCB. You wouldn't normally use 16A for a lighting circuit.
I would expect the two white carriers to be the lights at 5A each.
Could you re-check that.....



When putting the wires under the floorboards are there any preferences with
repect to how I should route it? Currently all the wiring appears to go
into channels cut into the joists between the nails! I can now see how some
people can put nails through such wiring.

Exactly. Apart from being a bad idea for the joists, it is not
allowed in the wiring regulations either. You should drill a hole
through each joist at least 50mm down from the floor and 50mm up from
the ceiling below to avoid the risk of nails reaching the cable.



Anyway, to avoid me having to
take up more floorboards than I may need to, what is the opinion of drilling
a hole through a joist and running a wire through that?

That is what you should do.

I realise that this
will stop me from being able to move the wires around once all the boards
are up (whereas in channels they can just be layed down - possibly done that
way for ease of installation) - but realistically, when's that going to
happen?

Thanks.

D


..andy

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