Wiring for garden office - can I spur off an external socket?

[thatsimpsongirl]

Thanks to all of you for your replies.
I’ve attached a photo of the fuse box & the cables coming out of it...Not totally sure what I’m looking for?!

 

[brianmoooore]

B32 looks promising!

 

[Spoon]

Outside socket is on a 32A breaker

Bugger, @brianmoooore beat me to it.

 

[Dustydazzler]

You might be in luck of the outside socket is in 4mm cable you could piggy back off this

 

[thatsimpsongirl]

How about the hot tub/sauna?

? that's for the next reno

 

[brianmoooore]

You might be in luck of the outside socket is in 4mm cable you could piggy back off this

With no fused spur required

 

[thatsimpsongirl]

You might be in luck of the outside socket is in 4mm cable you could piggy back off this

Thanks. How would I find this out?! Here are the cables before the kitchen units were put in - it’s one of these...you can see the hole in the wall to the outside. I’m not sure if this is what you’re asking me though!

 

[Spoon]

I'm not sure what I'm seeing in that picture. It looks like coils of cables with about 4 cables going into the wall from the coil.
Is the outside socket behind the coils?

 

[brianmoooore]

If the outside socket is sized according to the regs., then it is a minimum of 4mm2.

 

[thatsimpsongirl]

I'm not sure what I'm seeing in that picture. It looks like coils of cables with about 4 cables going into the wall from the coil.
Is the outside socket behind the coils?

Sorry it’s not that clear is it! The outside socket is directly behind the wall with the wires on it - the kitchen is in now (well nearly - as you see) and the induction hob and a socket will be in this island bit, hence all the wires.

 

[loz2754]

What did W10 SAY then can't see his response.

Post number 5 I think Pete.

 

[brianmoooore]

Very roughly, what is the distance from the external socket to the new studio?

 

[thatsimpsongirl]

Very roughly, what is the distance from the external socket to the new studio?

About 5m. So not too far.

 

[brianmoooore]

In that case, a 32A supply to your studio should be possible. Go on from the outside socket with 4.0mm2 or 6.0mm2 3C SWA to a small non RCD consumer unit in your studio.
Only downside, is that the RCD for the studio will be indoors on the main CU, so if it trips you will lose all power to the studio, including lights, and you will have to go indoors to reset it.

 

[Pete999]

In that case, a 32A supply to your studio should be possible. Go on from the outside socket with 4.0mm2 or 6.0mm2 3C SWA to a small non RCD consumer unit in your studio.
Only downside, is that the RCD for the studio will be indoors on the main CU, so if it trips you will lose all power to the studio, including lights, and you will have to go indoors to reset it.

I'm surprised Brian that you would condone changing the size of the cable at the point of connection to the outside socket, not one person has asked if this outside socket is a spur or whether it is part of an RFC, apart from myself post 6, sorry for the disagreement to your reply.

 

[loz2754]

Hi Pete. I believe the OP has stated that the socket is fed directly on its own 32 amp MCB in the consumer unit.

 

[Pete999]

Hi Pete. I believe the OP has stated that the socket is fed directly on its own 32 amp MCB in the consumer unit.

 

[Pete999]

Right thanks for that must have missed that,

 

[brianmoooore]

It's not been verified that the existing outside socket is the only connection to a 32A MCB, wired in 4.0 or 6.0mm2 T&E, but the signs are promising. My last post does depend on this being true, of course.

 

[pc1966]

If, as it appears to be, it has a dedicated 32A MCB feeding it then it should be at least 4mm cable and plenty capable of feeding the garden office. When all of the current work is done the completion certificate should confirm that, along with various other measurements that would allow the correct design of the office electrics.

The only possible issue is what @brianmoooore pointed out - the RCD protection is in the house's main CU (fuse box) and shared with other circuits. Not normally a problem, but an extra inconvenience if a fault does develop (compared to separate RCD).

For sockets and lights in a small office style arrangement you almost don't need a 2nd CU in the out building as the lights could come off a FCU (fused connection unit), but for all the cost of a CU it provides a handy place to isolate and test circuits, even if the MCBs in it have little selectivity with the feed from the house.