Paul paul at javajedi dot com wrote:
I have a question for those expereienced electricians among us. I am buying
a new house,
and now that the second fix has been done and the CU installed I can see
that there is only a single ring serving the whole of the house sockets.
(additional circuits a lighting upstairs inc smoke alarms, lighting
downstairs, electric cooker).

I have serious reservations about this, as I was expecting two rings, one
upstairs, one downstairs.

I have done some reading of the uk.d-i-y FAQ, purchased IEE onsite guide to
16th
edition wiring regs, had a read on the web and spoken to the NHBC. The
general consensus of all
these is that the regulation states:

- Ring should not cover more than 100m^2

And thats about it. Now I am pretty confident that with a tumble dryer or
washing maching typically pulling up to 2-3KW each (washing machine is cold
draw only - Bosch), that all I have to do is boil the kettle (3KW) or have
the misses use a hairdryer (2-3KW) on washday and the ring will trip. Thats
not taking into account loads from things like Dishwashers, computers, TVs
and the like. This concerns me as (a) I have 2 computers I usually leave on
24/7 and they will not like it and (b) I have an alleregy to setting the
clocks on everything electronic and can barely cope with twice a year for
daylight savings!

It's unlikely that all these devices will draw all that power
simultaneously. Also, a hair dryer is usually only 750 to 100 watts,
nothing like the 2-3kW you suggest.


Looking at the builders brochure, although their figure of 1000sqft would
mean 93m^2, they have taken the main foot print of the building. Calculating
with the protruding garage area at the front, and the protruding kitchen
area at the rear (all served by the same ring) the foot print is over
100m^2.

My Question: Can anyone tell me a way I can express the single ring being
overloaded referencing the IEE regulations?

What you should really do is add up all the things you are likely to
have switched on simultaneously and then have a guess at the chances
of things which are on intermittently coming on simultaneously. You
may well find that the chances of tripping the circuit breaker are not
all that great.


I know that the 100m^2 figure is just a guide, but there are 34 sockets fed
from this ring, and I am sure I will be using nearly every one; its just not
up to the job. I am not sure how to prove that though quoting the
regulations, which is what I am going to need to do to get the builders to
take notice.

As you say the 100m2 is only a guide. 'Diversity' as outlined in the
OSG should also be applied, however you can only do this when actual
appliances are installed, the builders aren't really able to do it.

Having said all that I too would have expected two rings in a modern
house. How big a house is it - i.e. how many bedrooms etc.?

--
Chris Green )