Additional supply to garden shed

levstar · 7 Jul 2008

Hi
I have a 13amp fused spur providing plug sockets to my summerhouse at the end of the garden (this socket is fused).

I now have a shed next to the summerhouse and would like to split the supply from the summerhouse and add two sockets in the shed.

My question is can I do this by adding a 13amp fused spur from summerhouse to feed two plug sockets in the shed?

Thanks

Ian

ban-all-sheds · 7 Jul 2008

No point in doing that.

Are you comfortable that you know enough about what you're doing to design it correctly, and install it correctly, so that when the council come to inspect & test it it will pass?

levstar · 7 Jul 2008

Yeah, quite happy, what would you suggest is the best approach?

Cheers

ban-all-sheds · 7 Jul 2008

Just extend the circuit to more sockets, ensuring, obviously, that you use the correct cable for the environment where it will run, and the correct installation methods, and that your R1+R2 value remains within limits.

levstar · 7 Jul 2008

Ahh so no need for another spur then, I take this is because its already running from an existing spur.

Re extending the cable as I will not be using a spur to join the new cable for the shed supply is it acceptable to use a choc block housed within conduit housing to join the new cable?

Thanks for your help on this.

ban-all-sheds · 7 Jul 2008

As long as it will be accessible for inspection, and the cable type you're using can be used with choc-blocks.

But why not branch off at a socket????

levstar · 8 Jul 2008

Cheers,

Thanks for this information, it might be easier / tidier for me to break the cable before the socket and run some new conduit to the shed.

Cheers

levstar · 16 Jun 2010

Hi following on from this advise given a while back, I have now moved and want to basically do the same again however there are some differences at this proerty.

1. I have 13amp fused spur from the ring final on the downstairs living room circuit feeding an outside light. This has been taken off of the ring using 1.5mm cable.... is this allowed, should I upgrade this short piece of cable to 2.5mm T+E?

2. I was going to dis of the outside light and run some 1.5mm T+E I have up the garden approx 30 ft in some conduit I also have to supply some sockets and pointentially a light. (sockets only to be used for light use no heaters etc). Is this ok to do?

Thanks in advance

Taylortwocities · 16 Jun 2010

levstar said:
Hi following on from this advise given a while back, I have now moved and want to basically do the same again however there are some differences at this proerty.

1. I have 13amp fused spur from the ring final on the downstairs living room circuit feeding an outside light. This has been taken off of the ring using 1.5mm cable.... is this allowed, should I upgrade this short piece of cable to 2.5mm T+E?

2. I was going to dis of the outside light and run some 1.5mm T+E I have up the garden approx 30 ft in some conduit I also have to supply some sockets and pointentially a light. (sockets only to be used for light use no heaters etc). Is this ok to do?

Thanks in advance

There is no way to determine what your load will be but I would expect that the volt drop would be too much if you only use 1.5mm. That would only really work if the circuit was only for lighting.

So in answer:
1. Upgrade to 2.5mm all the way from the FCU.
2. You should use armoured cable, not conduit.. Where will the cable be run? Surface (what surface, fence, wall??) or buried (what is it buried under, lawn, flower beds??)

levstar · 17 Jun 2010

Hi in the previous job I did as per above posts I used the 1.5mm cable to supply my sheds, this seemed to work fine as I only used the power to supply a light, lawnmover and occasional power tools drills etc.

Although 2.5mm was used from the ring to the FCU.

I was going to run the cable undergroung to the shed and as I have loads of 1.5mm and conduit left over thought this would be the most economical way.

Taking on board what you said re voltage drop, is this safe to do?

Thanks for your help

ban-all-sheds · 17 Jun 2010

levstar said:
I was going to run the cable undergroung to the shed and as I have loads of 1.5mm and conduit left over thought this would be the most economical way.

It might be the cheapest way, but it is not the right way.

Taking on board what you said re voltage drop, is this safe to do?

No - use armoured cable.

Steve · 17 Jun 2010

plastic conduit is not suitable for protecting a cable outdoors from anything.

levstar · 19 Jun 2010

Ok fair comment I will purchase some SWA.

Looking at a diagram on page 362 of the regs it looks as thought I can us 1.5mm from the fused connection unit am interpretting this correctly, as the 13 amp fuse will provide protection on the downsized cable?

Thanks

Taylortwocities · 19 Jun 2010

levstar said:
Ok fair comment I will purchase some SWA.

Good

levstar said:
Looking at a diagram on page 362 of the regs it looks as thought I can us 1.5mm from the fused connection unit am interpretting this correctly, as the 13 amp fuse will provide protection on the downsized cable?

Thanks

13amp fuse on 1.5mm² cable yes but you also have to consider volt drop.

You need to do cable calculation to work out if the vd is within specified limits for
your maximum load (do you know that?)
and the length of the circuit (do you know that?)

As you only bury cable once, and digging a half metre deep trench is a lot of work, then I would future proof the installation by being OTT on your cable sizing. One day you may want to turn the shed into an office and run a 2KW fire in there......

ban-all-sheds · 19 Jun 2010

Taylortwocities said:
You need to do cable calculation to work out if the vd is within specified limits for
your maximum load (do you know that?)
and the length of the circuit (do you know that?)

And you need to condsider what the earth fault loop impedace will be at the far end.

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Additional supply to garden shed

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