Electrical Quesitons

[Charles Middleton]

I was expanding some plug sockets from singles to doubles in my house the other day and noticed the following. I powered off what I though was the upstairs sockets and set about testing them to make sure that they were not live before I comenced work.

It was at this point that I noticed that my downstairs sockets where off as well. To cut a long story short it seems that the house is wired up basically with two MCB's - one for the kitchen and one for the rest of the house. Not sure at this stage of the rating. So all of the sockets in the house less the kitchen are wired onto one ring circuit.

As 2.5 twin and earth is rated at 25 amps and I only have one circuit for all of the sockets, this means a maximum load of 25 amps and I make that a maximum of 5.5kw. Is that correct?

Im just hoping that this will be enough for all of the stuff Im planning to run.

- 2 x PC's probably running most of the time including permanently switched on router. - Home cinema system running intermittently - Various other appliances, vacuum cleaner, phone chargers etc.

What do people think? For info the house is a two bed semi so perhaps the developers didn't think that two ring circuits (upstairs and downstairs) would be required.

CM.

[Wheelbarrowbob]

Check at your consumer unit , for the rating on the MCBs, generally speaking the highest rated circuits will be nearest the main switch, ie 45A for a shower, 40A for a cooker, then your ring circuits, should be 32A and or radial circuits 20A there maybe a 16A and lighting circuits 5 or 6A. There will be B6A marked on the mcb which means type B 6Amp mcb. If you have 2 32A ring circuits in a 2 bed house you are no differnt to most people, and pcs dont consume that much power,and even if you plugged all your toys into socket circuit at once i doubt you would overload it

[Ric]

Most likely the case - we live an a three bed semi which was originally wired with one ring for the whole house. When we built a kitchen extension we extended this ring to the kitchen as well and we have never had any problems - I run various PCs, a home cinema set up and loads of other things! Remember that most of the things in your house that need a high current (immersion/shower/cooker/etc) run off their own circuit so the things you mention generally don't have a very high current drain and should cause you no problems.

[usenet]

It's probably much more sensible, if you are going to have only two rings, for one to be the kitchen and the other to be the 'rest of the house'. You're much more likely to get a reasonable balance of load between the two rings that way.

But it's a ring so you can have a total load of up to 32 amps on it (it is protected by a 32 amp breaker is it?). If fused it will be 30 amps rather than 32.

32 amps at 230 volts is just under 7.5kW.

All of 500 watts I would think, maybe a little more, say 750 watts.

Another 500 watts or so at a guess.

Nothing except electric heating will take much more than a few hundred watts. A really big vacuum cleaner might be just over 1kW. Phone chargers etc. take only a few watts.

Thus if you add it all up your still at only two or three kW, it'll be fine unless you plug in two electric fires *and* decide to boil the kettle in your bedroom.

[Lurch]

On Fri, 30 Apr 2004 11:07:27 +0000 (UTC), in uk.d-i-y "Charles Middleton" strung together this:

Quite common, most new houses that I wire are done similarly, 1 ring for the front and 1 for the back. It makesx wiring easier.

Depends, if they are ring circuits then there are 2 cables to each socket in effect, the MCB\ fuse size for this is 32A so that's your maximum. This is more likely to be what you have. The other way of doing things would be a radial, with 2.5mm cable you will only be able to have 16A. The cable ratings are maximum - in ideal situations. In practice they need derating because of the way the length\resistance and thermal effects lower the current carrying capacity of the cable.

2 rings will be fine for what you want, 2 PCs, home cinema and phone chargers will probably struggle to peak at 10A if all switched on together.

[Charles Middleton]

Thanks for the info. Sounds like I'll be alright. Probably worrying about nothing as usual!

CM.

[Z]

In article , Charles Middleton writes

That's common. There is regulation to minimise the effects of interruption of supply to a circuit. Just interpretation what disruption is caused and how crtical it is to have a circuit trip. You wouldn't want to have the washing machine stop 3 minute before the end of a cycle because something somewhere else had tripped a breaker. Perhaps consider more ring mains and/or washing m/c circuit fridge freezer circuit.