Which Wire??


Postby Pearcey » Wed Jan 21, 2009 1:59 am

I am currently buying electrical supplies to re-wire my house. I wondered what cable was required for:

The power point for an oven??

The power point for a combi-boiler??

An electric fire??

Cheers
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Postby kbrownie » Wed Jan 21, 2009 12:39 pm

Depends on the rating of the equipment which will determine the protective device needed, then the installation method the length and route the cable may take 9ie through thermal insulation) need to be considered. If the cooker switch has a socket on that will aslo have be accounted for.
I suspect that this is not your day job, I would advise you take a look at the projects page. Start at project part p: http://www.diydoctor.org.uk/projects/partp.htm find out the legal requirements of taking on a job like this.
You can do it this a diyer but building controls need to be involved and they will charge a fee and the installation will need to be inspected and tested, to assure it safe and complies to BS7671 and part p.
KB
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Postby sparx » Wed Jan 21, 2009 9:57 pm

This is one of those frightening posts that shows why electrical work is now a 'controlled service' covered by Local Authority Building Control.

Sir, the fact you are asking these questions shows you are not competent to carry out a rewire safely, never mind test and certify the end result as required by the regulations. BS 7671 may not be law, but nor is highway code, both have similar status.
As KB says there is no direct answer, these sizes have to be calculated.
In Spite of dodgy displays in DIY stores suggesting:
1.5mm for lights
2.5mm for sockets
6mm for cooker
it just ain't so, what about the consumer unit, are you going to try to change that also? I trust not!
Sorry, but this is a professional job, apart from anything else if you ever want to sell house lack of certs. will be a problem, also insurence companies will use it to get out of paying if heaven forbid a later fire occurs .
Please reconsider,
regards Sparx
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Postby Pearcey » Thu Jan 22, 2009 3:10 am

Thank you gents for a quick response.

I am not planning to undertake the work myself. I am just buying the supplies myself as i can get hold of them cheaper than what the electrician who is doing the job could (Mainly due to his mark up on the supplies)and was just looking for some guidance as to the size of wire to run to the said appliances.
It is a complete re-wire of an old terrace and a new consumer unit will also be installed. Most of the wiring that was in the property was very old and the wires were actually in a cloth like sheath.

I shall quiz the sparky as to the correct wires to match the size of the appliance.

Thanks
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Postby singer » Thu Jan 22, 2009 12:36 pm

Oh my Word another penny pincher.

Anyone will tell you that the majority of the cost on a rewire is not the materials but the labour to provide the knowledge and expertise to be able to do the job safely and proffesionally.

The money you will save by getting the materials yourself is not worth the hastle.

I've done work like this before for customers who buy their own materials and my experience is they count up the number of lights & sockets and buy the exact number of fittings and not enough cable, without any thought for breakages, faulty fittings or extras.

They never think of junction boxes, sleeving, earth wire, channelling or trunking, meter tails, plaster, grommets etc etc which then holds the job up which causes more labour charges which defeats the whole exersise.

Not worth it mate!!
Accept the electricians quote & leave it to him!!!!!!!
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Postby kbrownie » Thu Jan 22, 2009 3:38 pm

I think that would be for the best, you could calculate them yourself, if you had the tables with all the rating and factors on. These tables can be found in BS7671:2008 and The On-Site Guilde. But these books would cost about 75-80 pound.
That money could be spent on 300 meters of cable. There are general rules regarding ring and radial circuits depending on area covered.
I hope you can appreciate the safety aspects concerning electrical installation and sometimes it may seem that replies to post are unhelpful.
But I like others feel that we just can't go giving advise out if we feel that the person undertaking the work does not have the understanding or the experience to carry this work out.
It's a matter of safety.
KB
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Postby sparx » Thu Jan 22, 2009 11:57 pm

Well put Singer,
we have all been there & no way would I do a job using customer supplied cable & accessories.
Some of the cheap cable around is so difficult to thumb out & strip it takes twice as long, sockets costing over £4 in DIY sheds are rubbish compared to wholesalers quality items costing us much less.
Pearcey would your local garage fix your car with parts you supply?
I think not!
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