Installing power to my shed ???

[Tyrone4233]

Hi everyone,
Just need alittle advice, I would like to install power to my shed, the way I was thinking is to link off my existing downstairs ring using a switched fused spur, from that using a 2.5 swa to my shed into a 3 way consumer unit fitted with a 63amp 30mA RCCB, using 6A mcb for lights & 16A mcb for sockets.
Does this sound about right, If not where am I going wrong, any help would be greatly appreciated.

cheers Ty.

 

[Steve]

If you spur off the downstairs ring, chances are you wont need a RCD or any MCBs - forget the consumer unit in the shed.

Is the downstairs ring RCD protected? If so, you can omit RCD at shed.

What distance are we talking to the shed?

 

[Taylortwocities]

And what will we be running off those sockets? MIG welder, lathe, or just a lawn mower.

 

[LoveRocket]

IF the load in the shed is only going to be small (ie basic hand tools and a radio) and IF the downstairs ring final is RCD protected, then just go from an FCU on the ring out to your shed, then straight to the sockets. Then use a switched FCU with a 3a fuse for your lights.

Easy.

 

[Tyrone4233]

Thanks for the quick reply chaps, we're talking from the house ring to inside the shed is about 7 metres and yes just for lawnmower and battery charging. My main cu has the old rewirable fuses so I thought it would be safer to use a 30mA rccb. What do you think ??

 

[Taylortwocities]

My main cu has the old rewirable fuses so I thought it would be safer to use a 30mA rccb. What do you think ??

It is not only safer, it is essential.
A RCD-protaected switched fused connection unit would be the best bet.
Your armourde cable will need to be buried a minimum of 450mm if it is to run under lawn/flower beds etc.
And you will need to tell your local authority (and pay their fee) before you start as this is notifiable work. Or use a registered electrician.

 

[Tyrone4233]

A RCD-protected switched fused connection unit ??
Would I install this on the spur off the ring then run the swa from this to the shed (sorry to sound thick) could I still do it using 3 way cu with fuses as I already have this ?? I also have a 13A switched fused spur ?? and is 2.5 swa big enough ??

 

[Steve]

A RCD-protected switched fused connection unit ??
Would I install this on the spur off the ring then run the swa from this to the shed

Yes.

Given you have an old rewireable fuse box, I'd be looking at getting this replaced asap to give you better protection through your house. It could one day save your life.

 

[Lectrician]

Forget the CU - You will end up with a 16amp breaker for the sockets which is larger than your 13amp FCU......

I would run a spur from the ring, via an FCU to the shed. Link around all your sockets and use an FCU to switch a light, as mentioned above.

Use metal clad sockets for mechanical protection and to give the SWA something to gland into. Idealy conduit for your internal cabling, atleast in the vulnerable areas.

Depending on the size of the shed, probably just a one double metal clad socket, joined to a metal clad SW-FCU with a galv coupler and two brass bushes. Conduit or T+E upto a light fitting.

An RCD FCU is something like this: http://www.screwfix.com/prods/14770/Electrical-Supplies/RCDs/Powerbreaker-13A-RCD-FCU

There are cheaper around.

2.5mm is fine for your load and length.

 

[LoveRocket]

could I still do it using 3 way cu with fuses as I already have this ?? I also have a 13A switched fused spur ?? and is 2.5 swa big enough ??

Yes you can, your original plan would work and would be safe - although it would considered bad design as you'd have a 16a MCB downstream of a 13a fuse. (although in reality a B16 MCB would likely operate before a BS1362 13a fuse). The other benefit would be that you wouldn't have to go back to the house to reset the RCD.

You are so close to doing a good job of this, is it not possible to take the SWA back to the CU?

 

[Tyrone4233]

that would be a real pain as the main cu is at the other side of the house, could I do away with the 13 amp fuse spur all together and use a junction box on the ring into a metal clad box straight onto a swa out to a shed or what about using a 20A switched fuse spur ?? thanks for everyones advice on here it's been really helpful and very interesting.
cheers Ty.

 

[Taylortwocities]

The is no such thing as a 20A fused spur.

 

[LoveRocket]

that would be a real pain as the main cu is at the other side of the house, could I do away with the 13 amp fuse spur all together and use a junction box on the ring into a metal clad box straight onto a swa out to a shed or what about using a 20A switched fuse spur ?? thanks for everyones advice on here it's been really helpful and very interesting.
cheers Ty.

Nah. If you're coming off a ring final you are limited to using a 13A FCU.

As I've said, whilst your proposed design isn't the most elegant, in the real world it sounds perfectly sufficient (unless you plan to start a welding college in your shed) and safe. Just make sure you terminate the SWA properly - oh, one more thing, are there any extraneous conductive parts in your shed (metal water mains etc)?

 

[Tyrone4233]

http://cgi.ebay.co.uk/Newlec-NL8413...ls_Supplies_Electrical_ET&hash=item20ae88e46e

 

[ban-all-sheds]

Very funny.

Who would you rather believe?

Some tw@ on eBay, or the manufacturer?

http://www.neweysonline.co.uk/newle...witched/1000009125/ProductInformation.raction