Running Cable To Shed

[annieigma]

Hi All,
Nice to be back again. hope builder is still about. question: need to run a cable to newly built sun room? wooden garden shed. it is only basically a wooden shed, and i would like to have a 13a socket and a light in there. it's no more than 10 mtrs away from the back of the garage, which has 13a sockets. any ideas how i should do this please.

[malagabob]

Armoured cable is a starting point But you'd have to calculate voltage drop to determine electrode size.

[The Builder]

Assuming the garage sockets are on a "ring" circuit, you could simply run a spur from the garage to the shed, but it does mean making certain tests. Only an electrician could decide. There are several things to take into account.

The best way is to run an armoured cable 450mm deep from the socket to the shed. Connect the live and neutral, but NOT the earth.
Inside the shed, install a "garage unit". A simple consumer unit fitted with an RCD, a 16amp breaker for the sockets, and a 6amp breaker for the lights.

Drive in an earth rod just outside the shed, and connect to the garage unit. The external impedance of the earth rod would have to be measured. It's essential that the shed installation and the armoured cable are electrically protected.

It's not a major job, but it really should be carried out by a qualified electrician, annie.

[annieigma]

Thanks builder, sounds good, but can you explain why the pme earth
in the house is not suitable for the outbuilding? i thought earth rods were old fashioned?
Also, sorry to tax your brains again, but my Son has built the frame to a bin cupboard, about 3 mtrs long by 1.5mtrs square. He went to wickes, saw some wood to clad it with, strips of semi hardwood 6mm x 76, coated it with some clear preservative. Cost an absolute fortune, about £7 a 2,4 strip, He needs loads more. any idea of an alternative please. It needs to be a whiteish wood, planed that can be clear weatherproofed, unlike the wood he used, which I looked up on wickes, was for indoor use and more for pretty decorative use.
Thank you again.
Annie.

[Georgiesmum]

Definitely a job for a qualified electrician.

[The Builder]

Annie, you may well be able to "export" the earth from the garage to the shed. That's why I mentioned that a bit of an assessment is needed to decide if it's possible. It would depend on how the garage is wired, and whether the impedance measured from the shed would be low enough (technical talk!)

Earth rods are fine when used in conjunction with an RCD. It may well not be necessary. The reason for using one is simply to isolate the earthing of the shed system from that of the main house. It's not always a good idea to export an earth for various technical reasons.

Have someone assess it and decide if using the house earth is viable.

For the timber... treated timber is best, but it isn't usually available in planed form. "Feather-edged" boarding as used on garden fences is often used. For trouble-free materials, uPVC cladding is now available in various "wood" colours. No maintenance at all.

http://www.nationalplastics.co.uk/external-cladding/woodgrain-cladding.html

[Old_Geezer]

This isn't a cable length issue.
If you are intending to spam for your company then I predict a short term membership.

[annieigma]

Thanks everyone,
The builder< The garage is fed from the house consumer unit in an armoured cable, and there is another small consumer unit inside the garage that the armoured is terminated at. I was thinking we could do the donkey work of digging the trench, drilling the hole in the garage wall and taking the cable into the wooden shed. I assume the consumer unit for the shed would go at high level, the one 13a double gang socket fitted about 800mm from the floor. Looking at cable sizes, would a three core 1.5 be sufficient?
Thanks again,
Annie.

[alavahalf]

We did my sons about a month ago and ran 30 mtrs of armoured cable under 2 concrete paths and the foundations of a wall. Drilled the holes in the shed base and the garage to feed the cable through. It was only a couple of hours work for the electrician to make the connections at both ends. He didnt want the job if he had to do the donkey work. So yes, you will save yourself a fair bit if you do the groundwork. The cable alone cost us £250 .. then another £150 for the rest of materials.

[Old_Geezer]

No expert but my thought is that a larger cable than needed is less bother than a thinner one that drops too many volts over the length and needs replacing.