Supply for outbuilding

[Nicktric]

Hi, I have been asked to supply an outside office(shed) with one socket and lighting. There is no metalwork in there. Can somebody point me in the right direction with regards to regs about clipping SWA to permanent boundaries and when or if you are allowed to clip SWA to a fence, what height etc? I'm sure this has been covered but couldn't find it quickly? I am planning to use an S type 20A RCBO with a 15M run of 4mm SWA clipped to strong concrete post fence.... to a Volex 40A RCD garage unit 16 +6A mcb's. Any concerns with this? Anything else I need to think about? Cheers

 

[Deleted member 26818]

I wouldn't bother with an S type 20A RCBO (I didn't know such an item existed), if you are using SWA.
I'd use a 32A MCB to protect the SWA, then a 40A main switch in the garage CU, with a 20A RCBO for the socket and a 6A MCB for the light.

 

[Nicktric]

Thanks SPin, I'm not sure it does exist but thought it would be a good solution for RCD discrimination but like your setup. However as the CU comes with 40A mainRCD and 16A and 6A mcbs suppose I could use a RCD socket? Any thoughts on the SWA clipped to the fence if it is permanent and solid? Thanks

 

[malcolmsanford]

You may have to think of RCD protection if the installation earthing is via TT, for that SWA if you can not get a low enough Zs for the sub main.

Yes I see no problems with cleating the SWA to concrete support posts, but you may also find you need to cleat it to the fence as the distance between posts are normally 6ft when using fence panels.

As this is an office are you convinced that 1 socket is enough. What about telephone and data?

 

[Deleted member 26818]

No need for an RCD socket if the CU mainswitch is an RCD.
There's nothing in the Regulations about clipping SWA to fences, so you'll have to assess how robust the fence is and whether it's man enough.
I wouldn't be happy clipping SWA to flimsy Larch panels, but I'd be happy clipping it to concrete base boards.

 

[telectrix]

or, you could mount some 2"x1" timber on the concrete posts and cleat your SWA to that.

 

[Nicktric]

Thanks Guys, the shed/office is for a student to study and she only needs a laptop + kettle but fair point. Like the idea of a suitable rail between posts to clip to. Haven't been to the house yet but will investigate SWA protection at CU. Cheers.

 

[the pict]

I would be surprised if one socket will do a student, I have inspected a lot of accomodation used by summer staff usuall students and the ammount of electrical clobber they have is staggering, more so the girls, I would put in 3 doubles at least , Kettle PC Phone charger DVD player Telly ( for countdown) H Fi, games console and thats not even considering the other stuff the girls use, yes it is for studying Yeah right,
Oh and dont forget kids never ever turn stuff off the just pull out the charger lead, so perhaps the RCD socket might be a good idea I have had an occasion of the phone charger lead in a cup of tea and left on " Dude my lights don't work like"
Pict