Power to Shed & Lighting

Gurkin · Post by **Gurkin** » Tue Nov 06, 2007 12:46 pm

Hi All,

1st post. I found your site last week and have found it invaluable already, Good work!!

OK. I am trying to run power to my shed and would like a double socket for tools and a separate light. I've attached a diagram that might make it clearer. Is my method for the socket correct? And can I use 3 Core for the light fitting. I'm a bit confused about the type of cable to use due to the L1 and COM. I'm a novice and don't want to electrocute anyone.

All help is very appreciated - Thanks.

Post by **ultimatehandyman** » Tue Nov 06, 2007 1:52 pm

Hi Gurkin,

welcome to the forum.

Outside power is now covered by the part P police and so it should of been notified to them first or done by a part p approved electrician. Don't worry I won't tell them, but I just thought I would make you aware

Hopefully the cable supplying the shed will be protected by an RCD?

What type of cable is it?

Is it armoured cable?

Is the cable a permanent fixture or is it on a plug that you can unplug when you are not using it?

how does the cable get to the shed, is it burried underground, fastened to the wall or is it suspended overhead?

How far away is the shed from the house?

Can you tell us how long the cable is and what size fuse it is protected by?

Sorry for all the questions, but it will make answering your question easier.

Gurkin · Post by **Gurkin** » Tue Nov 06, 2007 5:00 pm

My father-in-law is an electrician (who I can't contact at the moment) and ran an outside socket (IP55) from a 13A fused socket in the kitchen. He then advised me to run a spur from the external socket to the shed.

It runs along the wall for about 1.5m and then underground using some heavy duty polypipe that I had laying around for a further 2.5 - 3.5m. The cable is buried about 10 inches.

He didn't mention an RCD??

The cable is 1.5mm 3 core plastic sheathed flex It looks like this
http://www.screwfix.com/app/sfd/cat/pro ... 7&id=12596
and is not armoured as the polypipe is really quite substantial.

The cable will be a permanent fixture.

I hope this info helps.

Rich-Ando · Post by **Rich-Ando** » Tue Nov 06, 2007 5:42 pm

i personally disagree with running a spur off any socket to feed the shed sockets & lights. low loading, ok fair enough but i just won't do it that way.

you MUST have an RCD to protect it. i'm not just talking regulations i mean for your own safety.
burrying any cable in the ground, it's supposed to be 18" deep whether it's PVC in conduit or SWA.

1.5mm flex is too small. especially if it is a fair distance.

Gurkin · Post by **Gurkin** » Tue Nov 06, 2007 6:09 pm

Thanks for your reply. Where or when should have the rcd been fitted? Can I just plug one into the socket in the shed when its fitted? I thought that the 1.5mm was ok as I was only going to run power tools from it. If it's a question of distance what would 1.5mm be suitable upto?

Rich-Ando · Post by **Rich-Ando** » Wed Nov 07, 2007 12:55 am

without digging out the regs book i honestly couldn't tell you. the only reason i don't know is because i wouldn't ever tryt o do it that way.
one thing i forgot to say: -

your diagram shows the light and socket on the same supply. the lights MUST be fused down from the sockets.

an RCD should be at "source". that way the cable supplying the shed is protected, so that if you put a spade through it, it's won't kill you.

as for cable sizes, a lot of what i called "cheap sparky jobs" would involve running a 2.5mm T&E to the shed and then fusing it down appropriately inside for the lights.

me, i won't do it any other way than: -

minimum of 4mm armoured or 6mm T&E with a 10mm earth to a fuse box in the shed/garage. internal circuits wired from that. RCD at source.
yes it's an expensive way but my preferred way covers all eventualities like somebody trying to run a welder off the socket (it has been done before and they wondered why it burnt out)

Gurkin · Post by **Gurkin** » Wed Nov 07, 2007 9:46 am

If I can avoid it I would rather not dig up the cable as I've just laid turf 2 weeks ago. I wouldn't be using anything as big a welder. Am I on the right track with either of these solutions?

Gurkin · Post by **Gurkin** » Wed Nov 07, 2007 9:47 am

Rich-Ando · Post by **Rich-Ando** » Fri Nov 09, 2007 5:50 pm

the 1st is wrong. the 2nd is more like it but not the way it should be done.

i know you don't want to hear it but 1.5mm flex is too small, you're asking for trouble. if you get it, thats the turf to lift up again when it is fully grown in. doing it now after two weeks it will still be easy to lift.

Gurkin · Post by **Gurkin** » Sat Nov 10, 2007 12:00 pm

Thanks for your advice once again.

OK, I've replaced the cable with 2.5mm as suggested, buried it 18" and realised the pipe the cable runs in underground is MDPE PE80 and not the flexible polypipe (sorry I got my terms wrong!).

You mentioned fusing down the light from the power. Instead of using a fused switch and a light switch, can I not just use the fused switch to turn the light on and off and not bother with the light switch? If this is OK what type of fused switch would I need? Also, would the connections be more straight forward than the L1/COM scenario?

Thanks again.

Rich-Ando · Post by **Rich-Ando** » Sat Nov 10, 2007 1:58 pm

yes you can just use the switched/fused spur unit to turn the light on ad off.
the connections would be easier yes because you won't have to take a feed to the light and a switch wire to the switch.
all you need to do is take the supply to the 13a sfcu and one wire from that to your light.
change the fuse for a 3amp one and you will be ok.

i wire them in larger size cables to cover all scope but for 1 socket for a freezer and a light you will be ok as long as you have isolation on the supply with an RCD.