Shed power supply

leswilkins · 25 Aug 2007

i am putting an extra shed at the end of our garden and am considering putting a power supply to it.

i had intended putting an outside socket using a proprietary kit to cover the part P regs and then extend it with either conduit or swa cable.
my problems are that the ground here is only a thin layer of soil over shellite so an 18" trench is not feasible. (as i don't have the puff to dig with a pickaxe and the wife flatly refuses to do it)

the building is a bungalow so a 3.5m overhead won't look to good and as we are on the top of a hill 2 miles from the sea it will be exposed to very strong winds most of the year.

Would it be legal to build a wooden rail structure about 1m high and 1m in from the garden boundary and attach either SWA or conduit to this.

any other ideas considered

briwire · 25 Aug 2007

I would feed the shed directly from the CU in the house, and it has to be protected by an RCD.

The latest regs don't actually give a deprth for burying cables, they just state that they must be deep enough to avoid mechanical damage. So you might get away with burying it. Failing that, there is nothing wrong with fixing it along a structure such as a fence, so long as it is firm and secure. Use SWA.

leswilkins · 26 Aug 2007

Thanks for the quick reply,

the reason i'm not using the consumer unit is because the property is housing association and although i have a fair grasp of electrics (retired commercial engineer) we cannot touch the supply without a certificate.

as the outdoor socket kits have a plug in rcd it seems the easiest option.

The reason for the rail is that the fence is chain link and i was thinking fastening to this would be unsafe so i thought a piece of 3x2 raised off the ground running the length of the garden would be a better option.

(i might be able to run the cable at about 8-12"deep along the side of the path with the indicator tape over it) but would need to run it along the side of a raised deck for about 8' of the 30' run

Aardvark Avo · 26 Aug 2007

if your going for the socket approach then you may want to consider SY CABLE over SWA as it is flexible and provides mechanical protection

Steve · 27 Aug 2007

briwire said:
I would feed the shed directly from the CU in the house, and it has to be protected by an RCD.

The latest regs don't actually give a deprth for burying cables, they just state that they must be deep enough to avoid mechanical damage. So you might get away with burying it. Failing that, there is nothing wrong with fixing it along a structure such as a fence, so long as it is firm and secure. Use SWA.

1. The cable needn't have RCD protection, it is best practise to locate the RCD in the shed/outbuilding.

2. 450mm is the accepted minimum.

3. The regs require a wall or solid structure. A fence does not fall into this classification.

leswilkins · 30 Aug 2007

i have decided that if possible i will take the feed from the consumer unit and put a weatherproof consumer unit with an rcd in the shed. (it will be tested and certified by a local electrician).

as for the cable (swa). i forgot to mention that the ground here gets waterlogged in the winter so its probably best to run it a above the surface on a wooden board attached to posts cemented into the ground. it will be fixed next to the path about 2' in from the fence.

I really cannot see any other way of doing it as it will not be possible to dig to 450mm (i have to grow all the veg in my garden in raised beds because the ground gets so wet in the winter that everything rots).

also do the sockets and light fittings in the shed need to be IP rated and will it be ok to use flat twin and earth in pvc conduit for the internal wiring.
(1x13A twin socket and a single light)

Cremeegg · 30 Aug 2007

Its a lot easier running singles in conduit than trying to get T&E in conduit especially around any tight bends. Depends how waterlogged your shed gets as to what IP rating you want. I'd go for IP54.

RF Lighting · 30 Aug 2007

leswilkins said:
as for the cable (swa). i forgot to mention that the ground here gets waterlogged in the winter so its probably best to run it a above the surface on a wooden board attached to posts cemented into the ground. it will be fixed next to the path about 2' in from the fence.

SWA is completely waterproof

You could run it under the north sea if you like

leswilkins · 31 Aug 2007

Thanks for all the advice lads.
I've taken it on board and am waiting for the shed to arrive and a local sparks to give me a quote.
Regards
Les

leswilkins · 31 Aug 2007

the only reason for using flat twin was that i already had some but i agree with the point about singles

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Shed power supply

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