"Lurch" wrote in message
...
On Wed, 5 Oct 2005 16:25:55 +0100, "Fred" scrawled:


"Lurch" wrote in message
. ..
On Wed, 5 Oct 2005 09:13:33 +0100, "Fred" scrawled:

I find it surprising, will the IEE and authorities hell bent on reducing
risk - Part P and all that, that a ring main based on 2.5mmT+E is still
allowed. In most environments 2.5mm is not up to passing 32A which is
an
every day possibility.

When? You sure you've not got ring and radial mixed up?
--
Stuart @ SJW Electrical

Please Reply to group

From a current perspective, what's the difference. Suppose we have two
sockets close to one end, say nominally 1/10 into the ring. 9/10 of the
MCB
breaking current will pass through the shortest path. So yes a radial
circuit can then take 10% less current.

Hmmm, don't think it's quite as simple a calculation as that.
--

Short leg 10% of resistance of ring. Long leg 90% resistance of ring. The
voltage drop is the same across both legs. Simple ohms law - short leg
carries 9 x current of long leg. Add the two legs together to get (90% +
10%) = 100% Where do you think I'm going wrong?