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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Electrical Questions >> Wiring a garage https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1315067167 Message started by join1310er on Sep 3^rd, 2011, 5:26pm

Title: Wiring a garage
Post by join1310er on Sep 3^rd, 2011, 5:26pm

Hey everyone,

Im looking to wire up my garage and a little phased at what mcd i will need for my main consumer unit in the house, and which rcd's ile need for in the garage, ile be looking to put 4 fluorescents lights in the and around four sockets, i was almost sure i was going to use a 6amp and a 32amp, but on looking for a garage unit, theyre selling with a 6amp and a 16amp, will this be sufficient?

Thank you :)

Title: Re: Wiring a garage
Post by CWatters on Sep 3^rd, 2011, 5:57pm

Will depends what you want to do out there. Can the supply to your house handle another 32A? (Ok so it won't be 32A but you know what I mean).

Boring bit...The regs require you to use an electrician or make a Building Control Application.

Title: Re: Wiring a garage
Post by join1310er on Sep 3^rd, 2011, 8:33pm

basically as a workshop for general diy as and when required to be honest, the downside about getting an electrician in is the cost which i dont unfortunately have funds to throw around, hence me asking on here.
Thank you

Title: Re: Wiring a garage
Post by CWatters on Sep 3^rd, 2011, 10:54pm

I'm not actually an electrician (my background is in Electronics) but..

Most DIY power tools are 1kW or less. 16A is >3kW so would normally be ok.

My understanding is..

You need to select the cable size (in square mm) to suit the load current and the distance from house CU to garage. I think there might also be impedance issue but you need an electrician to answer that.

Then you need a breaker at the house end to protect the cable (in my case this is a 32A MCB so I believe the cable will be sized to carry at least that much under fault conditions).

In the garage CU I have an RCD and two MCB - a 6A one for the lighting and a 16A for the power.

The earthing arrangement needs care. I don't think you can allways export an earth from the house to the garage. You may need an earth spike near the garage (as I have). Need an electrician to comment on the rules for this.

Title: Re: Wiring a garage
Post by sparxxxx on Sep 4^th, 2011, 12:34pm

Have a look at this, you want issue 16 the first item - http://electrical.theiet.org/wiring-matters/2005.cfm

As you will see there are many issues to be considered. And employing a spark might not be that expensive, but its important to get it right.

Title: Re: Wiring a garage
Post by baz on Sep 4^th, 2011, 11:36pm

Some basic questions:

Is this garage attached to the house, or some distance away?
If it is some distance, what is your preferred method of running cables:
Underground, suspended cable, along the fence, etc? (wireless ;D)

Does your consumer unit have any spare ways?
Are any of them RCD protected?
Do you know what sort of supply type you have (TN-S, TNC-S, TT, etc?)

Title: Re: Wiring a garage
Post by join1310er on Sep 5^th, 2011, 9:53am

sparxxx
thank you for the link, that info is just the ticket. greatly appreciated.

Baz, hmm, good question, would you be ok to describe the difference it would make through the choice of mcb etc.

And it is rcd protected, probably a ten year old consumer unit :)

Installation wise i was planning 10mm armoured cable and running it under ground, the garage is around 10/15 metres away from the house,
Thank you guys...

P.s, out of curiosity, with the description i have given, what sort of price range would i be looking at for installation, considering all materials are on site and ready to install? i know it is a long shot bearing in mind it would be a blind estimate, just for knowledge of it would be great, seemingly ever more likely i'le be paying for it, lol.

Title: Re: Wiring a garage
Post by CWatters on Sep 5^th, 2011, 1:28pm

10mm might be bigger than you need. Might be of interest..

http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html