garden room electrics.

northdublin

planning to build a garden room at the end of the garden, i say room cause it will be a hobby room as opposed to a storage shed. ill also be using some power tools , nothing too heavy drills and routers and stuff like that.
should i put a sub board in the new shed and run a 16 sq off the existing board to feed it or should i just take off a sepatate mcb for the lights and sockets and send a feed down from there to the shed.
on the fitment end of things it will have three 2x58 watt corosion proof lights and about 10 sockets. on the outside it will have 2 bulkheads on a photocell with cfls and a switched halogen.
ill be running phone and alarm cables and i plan to put these in the same ducting as the mains,(esb ducting) could this cause a problem or should i run them separatley. many thanks

Stoner

I'd go for the sub board northdublin, just a small single row one. Then you can localise the whole shed and not impact on anything in the house.
I'd feed it from a 32 Amp MCB in the your main house, I'd bring a 16sq earth down with it too. Then use an RCBO for the sockets or MCB through an RCD, and a 10 amp mcb for the lights.

TBH running the phone and alarm cables down the same pipe is not ideal, but its a shed and you will be using 16sq. SWA. You are always better off seperating the LV and ELV, so if you can you should. I'd also opt for a polly polly cable for the phone and alarm, its more expensive but decent for underground arrangements, but sure you know all this already, I hope you don't end up paying too much for the gear!!

northdublin

ok stoner sounds good. ill be gettin the gear myself and doin all the donkey work but ill leave the final bit to a sparks just to cover my ass. would i be right in sayin that the 32 amp mcb will be on the same buzzbar as the lighting and heating circuts...ie not the rcd protected one . the reason i say this is there would be an rcbo in the sub board and i wouldnt want the house rcd to trip when the shed does......only the 32 amp mcb if something goes seriously wrong.
i was goin to use polly polly which will be exspensive as will 16 sq swa but i allways knew that would be the case. like my boss keeps tellin me copper is the new gold and the price of cable keeps goin up:rolleyes:

fishdog

Stoner, well said, I agree 100%.

i was goin to use polly polly which will be exspensive

No, this will be cheap enough. About 50 cent per metre (as far as I remember)

running the phone and alarm cables down the same pipe is not ideal,

This is correct, but because the SWA is shielded by the armour it should be fine in practice.

would i be right in sayin that the 32 amp mcb will be on the same buzzbar as the lighting and heating circuts

Correct.

SparKing

Lads I'm just wondering why you would bother going to the trouble and expense of running a 16sq. cable to a garden shed unless it's very far from the main consumer unit. Surely a 3 x 6sq. SWA (or 3 x 10sq. SWA at a push) would be more than adequate for a single socket circuit and a single lighting circuit.
I realise that you are covering yourselves by running 16's but in practise I couldn't see any electrician recommending that for a hobby shed/garage.

Stoner

sparking you make a good point, but i dont know if the cost of the cable would be such an issue to northdublin, we never asked how far the shed was away, I assumed that he could pick up an off cut of the cable due to his place of employment.
this question has come up a few times and anything from 6 to 16sq has been the answer (as one guy had a huge garden)
So yes I agree 6sq would do in many cases once the run was short. The 16sq gives futher scope for expansion though. So fair point, if you have to buy the cable 16sq is OTT.

fishdog

If in doubt go for the larger cable. This also means there is extra capacity. A more detailed question will get a more specific reply.:D

northdublin

thanks for the replies lads, the room will be approx 100 feet from the board so ill get the larger cable.

northdublin

putting in 12x 220 volt fittings in the garden and the jbs that came with the fittings are too small and pokey to get 1.5 nym into. would putting the connections into obo boxes using glands and then sealing with compound or that really sticky sh1t that comes in junction packs be acceptable. the obos would be just below the level of the soil. if obos are not ideal could wiska boxes do the job. the main circut cables are 6x 2.5 nym. each cable will have 6 gu-10 fittings with led lamps via trailing leads in 1.5 nym.

eoghan.geraghty

If you use obos, use the blue magic gel gear.
I'm sure you have it in stock, mix it up and pour it in, it sets like jelly in about 10 mins.