spur

[graham1]

Hi everyone.
I\\\'d like to add an outdoor socket. I\\\'ve found an internal socket that is connected directly to the fuse box. It has just one cable running into it. The distance to the fuse box from this is only 1 foot.
I\\\'d like to drill a hole directly through the wall and connect to this existing socket. The new connection would only be 1 foot long.
I know you shouldn\\\'t spur from a socket that has only one cable coming into it but is there any way to solve this as the position is ideal?

[cozycats]

If only a foot away wire it directly int the fuseboard. spur off a spur is not acceptable unless >4mm cable. Either way it's notifiable!

[Pens]

If I'm reading your post correctly and the cable feeding your existing socket is the only cable in that fuse way you can do as you propose as long as you do the following

1 The existing cable feeding the inside socket should be 2.5mm and the fuse/MCB rating must be no more than 16amps
2 If the inside socket is not protected by an RCD at the CU then you must fit a RCD protected socket outside.
3 The cable feeding your new socket must be 2.5mm

If socket inside is on its own fuse and there are no other cables in the fuse way when you add the new socket it’s not a spur it’s a new socket on a radial.

http://www.diynot.com/forums/viewtopic.php?p=327999#327999

[securespark]

The OSG lists a 20A radial feeding no more than 50m2 in 2.5 as acceptable.

__________________
As George Michael once said, "..if you're gonna do it, do it right, right?"

[Pens]

My mistake. It must be the J&B....and I don't mean junction box

[graham1]

Thanks for the quick response guys.
I've looked a bit closer at the CU.
The internal power socket runs 1 foot directly to a 32a MCB in the CU. This 32a MCB also feeds other sockets in same room.
So, after reading responses the internal socket isn't a spur but a new socket on a radial. Can I therefore spur from this with an RCD protected outdoor socket even though it's on a 32a MCB?
The outdoor socket will only be for some small decorative lights (similar to Xmas tree ones) if that makes any difference.
If this isn't possible what is suggested for wiring directly into fuseboard?
ie what MCB should I use?
Thanks in advance.

[Har_vey]

At the moment, if your existing internal socket is ran from a 32a MCB feeding two other cables then it is already a spur. So you can't run your new outside socket straight though the wall from that point.

Do you use the existing internal socket? If you don't then you could change it for a switched fuse spur, and then feed the new external socket from that. If you are only ever going to plug the lights in then protect the outside socket with a 3 amp fuse in the fused spur.

But, prior to starting, the whole of the circuit that you are considering altering will need to be checked to make sure it is safe, and if the existing sockets on that circuit are likely to be used for supplying equipment outside, ie. They are downstairs, then that whole circuit will need to be protected by an RCD, Not just your new outside socket.

You could wire a completely new circuit to feed your new outside socket from the consumer unit via a 16A MCB if you have a spare way? That would need RCD protection as has been mentioned.

Whatever you do there are checks and tests that need to be carried out with regard to the earthing arrangements and they need to be done before you start.

[graham1]

I need the existing internal sockets so unfortunately can't replace it with a switched fuse spur.
I do, however, have a spare way on the CU.
Can I make it a radial circuit from this spare way using a 16A MCB or does it have to be a ring?
As for the protection from an RCD, are there external sockets available with this built in or can you get these built into the MCB. If not, what's the easiest way to install one?
Out of interest, is it not possible to run a spur from one of the other MCB's in the CU?

[RF Lighting]

If you have a spare way in your fuseboard you could install a 16A RCBO and connect your existing socket to this, then connect your new external socket into the existing inside socket, or just wire the new outside socket directly to the new RCBO in your consumer unit and leave the old socket as it is. Whatever you decide you MUST notify your LABC about the work.

[Har_vey]

graham1 wrote:

Out of interest, is it not possible to run a spur from one of the other MCB's in the CU?

Yes. But from your point of view, it will be better to use the spare way to feed the outside socket. That way you only have to test what you have fitted, and not look at anything else. As has been said though, you still have to notify and you still have to consider the existing earthing arrangement.

You can purchase either an outside socket with a built in RCD, or as RF has suggested fit a 16A RCBO.

[graham1]

Will use the spare way and fit RCD protection.
With regard to notifying the LABC, do they have to inspect once work is done or is it purely for their records?
As for the downstairs circuit RCD protection, would replacing the MCB's with a 32a RCBO suffice?
Thanks.

[RF Lighting]

Unless you are a member of a self certifying scheme the LABC or their agent would come and inspect your work to make sure it is installed correctly and is safe. You will then recieve a certificate which you can use to prove compliance at a later date.

Fitting a 32A RCBO will be fine to provide protection to the downstairs sockets.

Rob

[daviegarden]

Graham, wire from your spare way with 2.5mm. Use a 20 amp RCBO in the consumer unit, that's all you have to do to comply with the regs. (apart from an earth continuity test, an insulation resistance test and a loop impedance test., if anyone is going to get particular about the added circuit). If you can't get an RCBO to fit your consumer unit, buy a separate 20 amp/30mA rcd with enclosure, mount it beside the consumer unit and supply it from a 20 amp MCB.