Advice on having electrical supply add to garage

Postby TLE » Thu Apr 17, 2008 12:45 pm


Firstly I will not be doing this myself, I will be contacting an approved electrical installer to get a quote for this work. I am just looking for some basic knowledge so that I know they are using the right components for the job.

1. My garage is about 3' away from the house and will require that the electrical supply be brought into the garage by a cantenary wire. What kind of cable should they be using, SWA or will be the standard grey stuff often behind walls?

2. What will they use to support the wire rope from the garage as this will be raised, I have see all sorts used on other people houses from, angle iron, round tubing to TV aeriel support poles.

3. I would like 2 flourescent lights in the garage and 1 double socket. With the possility to add some outdoor sockets for say the lawnmower and possibly a pond pump at some point in the future. What kind and size consumer unit should they be using allowing for some expansion, I don't want the minimum installing and then finding I have to have it replaced at a later date due to the load.

I appreciate all your help and advice if you have any, what too look out for when they are doing the job.

Many Thanks in advance.

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Joined: Thu Apr 17, 2008 12:35 pm


Simply Build It

Postby ericmark » Thu Apr 17, 2008 8:02 pm

I think you may be going over the top! For what you are talking about a switched fused spur for lights and all other sockets could all be fed from a 20amp supply as a radial from your house with 2.5mm² cable. As to what cable and how not really something which can be planed without being on site. I always try for steel wire armoured where I can and go under ground rather than use aerial cables. Main considerations is how it is supplied from the consumer unit. Ideal is with double pole RCD and MCB but this would depend on room available in the consumer unit and a RCBO may have to suffice. Again depending what is already in the house some old consumer units will not accept RCBO’s there are so many options. And the cost can vary so much my shed is fed from a 13 amp plug permanently plugged into a 10ma RCD socket mainly because they were in my spare box when I wired it.

Postby TLE » Fri Apr 18, 2008 8:30 am

Thanks for the response.

Are you saying that there isn't a need for a consumer unit in the garage? Forgive me for asking what may be stupid questions but I just want to be armed with as much information before I get anyone in to look at the job and I am struggling to follow your answer a little. I think in this case the cable will have to be suspended as patch and surrounding area is all concrete and I don't really want it hacking up.


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Joined: Thu Apr 17, 2008 12:35 pm

Postby ericmark » Fri Apr 18, 2008 5:34 pm

It is hard to judge not being on site as to what is required but unless you use your garage as a workshop then all that is really required is a radial circuit with a few sockets and a light using a switched fused spur instead of simple switch with 5 amp fuse gives you simple lights and reduces cost. RCD prices vary vastly a 13 amp socket can cost £20 where a plug under £7 and a metal clad switched fused spur is under £5 so if all you want is lawn mower, or hedge cutter, or drill etc. And one or two sockets where handy you could use a switched fused spur to bring power into a circuit in same was as out so short length of flex from RCD plug to spur unit to second unit in garage where switch runs your light with socket or two taken from unswitched side leaves meterial bill like.
2 x Switched fused spurs £4.69
1 x RCD Plug £6.59
5 meters of 1.5mm SWA £6.00
1 pack of glands £2.87
10 meters 1.5 flex £10
2 x Double sockets £3.40 (may be better with metal clad at £11.00 including backing box)
2 x Backing boxes 40mm £3.57
1 pack stuffing glands £5.00
1 pack cable clips £2.00
1 ceiling rose £1.50
Total under £60 where a garage consumer unit with cost £32 and you will still need most of what I have listed anyway plus a lot easier to make a gland into a metal back box than plastic consumer unit. I am reading between the lines and I think you really intend to do it all yourself. If you are really getting an electrician to do the job then since main cost is labour then may as well have consumer unit either way since fixed you should have Part P but I am a realist and think I know what most people say and do are not quite the same. Basically you are making a purpose built extension lead. I am sure I will get shouted at for suggesting this but it is so easy to get carried away and make things far too complicated. Also I have never seen what your garage looks like. I most likely have worked for far too many years abroad and I am always looking for easy way out.

Postby TLE » Mon Apr 28, 2008 12:22 pm

Thanks for all your help so far.

Sorted, I have an electrician who is going to do the job for me. He has asked that I install the support pole for the wire rope to suspend the cable on. I'm happy to do this as it saves a little on the job.

He suggested using a TV aerial mount and pole, would this be ok or is there a better method that someone can suggest. I have checked round and cannot find anything else similar, or that is designated for that type of job.


Posts: 3
Joined: Thu Apr 17, 2008 12:35 pm

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