detached garage supply

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mikel

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Please could I seek advice on supplying a detached garage with an electrical supply. The garage is approx 20 metres from the house. I was thinking of running a 10 mm t/e wire from the consumer unit in the house to the outside of the house, through an appropiate IP rated box into 3 core swa cable (using one core as the cpc) which would be buried between house and garage then into garage terminating it into a consumer unit and from there seperate circuits for lights /sockets etc each protcted by rcd's.

Would this be suitable? Any advice gratefully accepted as this is hte first time I've had to do a garage supply

 

extension15

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Why 10mm T&E?

What are you intending to run in the garage?

Is a 20A supply not sufficient? (Then use 2.5mm T&E & SWA)

; \

 
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Further, I`d do the swa conversion inside. Box is not exposed to the weather; and, from a purely logical viewpoint, SWA = round profile. T+E = oval profile.

Drill makes round hole. Which fits better?

And, as previously posted: Why 10mm?

 

Flying Scotsman

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Further, I`d do the swa conversion inside. Box is not exposed to the weather; and, from a purely logical viewpoint, SWA = round profile. T+E = oval profile.Drill makes round hole. Which fits better?

And, as previously posted: Why 10mm?
but a chiselling drill makes a square hole aswell :^O :^O:^O:^O:^O

 

mikel

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Job comes via a pplumber who is doing the heating etc for an extension, he had suggested to customer that the garage supply should be in 10 mm T/E and swa. I couldn't see any reason for 10mm but wanted to check I hadn't forgotten something or missed something. Box needs to be on outside as nearest part of Bungalow to garage (by some 10 metres) is a bedroom and customer doesn't want box on inside wall to bedroom.

Thanks for the advice, tis gratefully accepted. This place is so friendly and a good source of experience that is willingly shared :)

 

Nicky Tesla

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isn't anybody going to mention things such as; extraneous conductive parts; making the garage tt system; putting in a separate 10mm earth ; keeping the garage earth separate at the swa; and giving a link to the niceic garage supply page or anything this time, or are you all bored with this subject.

 

Nicky Tesla

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Unless your Tw&e is surface mounted the entire way you will have to put an RCD at the supply end. What is the Supply, TT, TNC-S ? If there is a water supply into the garage, you may need a 10mm earth. I would try to wire a SWA all the way.
surface mounted?

 
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Would run 2.5 T+E from a 20a MCBO or RCD protected circuit, to the edge of the house (internally) JB to 2.5 SWA (3 core I use 3rd core as an additional earth) out to garage, up to you if you put SWA in a protective pipe (I normally do). Run i into the outhouse/garage and back into another JB and onto either a board or spur for whatever you require.

If I put inanother DB I normally get a further RCD protected board, yes overkill but I always err on the side of caution.

Obviously you also have to consider earthing systems.

 

mikel

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Supply is TN-C-S, water into garage is in plastic pipe and all plumbing in garage is plastic. Was going to put RCBO at house DB and also DB in garage with circuits rcd protected just for safety sake and then if there's a problem in the garage it won't affect the house. One final question, I realise I need dscrimination with the protective devices. If I have RCD at originating DB and then one at garage DB do I need discrimination for the RCD's operating current or do I fit a time delayed one at house DB

 
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All depends if supply cable is buried at any point in house. If not then no RCD protection is required at house end. You are going to need to make garage tt as it is outside equipotential zone.

batty

 

extension15

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I see this thread has mixed views..

Don't think we are really answering the OP's question.

But 10mm SWA is OTT.

; \

 
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Here's 'that' document.

How can any one comment on if 10mm is OTT. You do not know the distance from the board to the point where the OP was to connect to the SWA.

My garage is wired in a 10mm Swa because i have a compressor, welder and other such tools in there. A lot of other garages i have wired have also had home workshops with possible higher current items. I don't agree with Batty about making this garage TT.

 
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Please note that the document i linked to above was written to the 16th edition and RCD protection is now needed to most Tw&e circuits, including the 'sub-main' to the garage.

Shocking and Mickel, 2 RCD's in line do not add any extra safety, In fact they can 'interfere' with each other causing nucence tripping.

If the Tw&e is not going to be surface mounted, a time delayed RCD does not meet the regs.

 

jckent

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1x 32A rcbo inhouse protecting 4-6mm 3 core swa. Mini consumer unit in garage rcd protected+2 mcbs(lights 6A/power16A). outter amoured earthed.

20M is not that far at all

4-6mm depanding on loading.

Job done

10mm well over top-pain in the butt to handle as well

 

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