Is my wiring diagram OK

Andrew32 · Dec 17, 2020

Hi
I am replacing the wiring in a lean-to shed that has a spur directly from the house ring main. I have done quite a bit of reading on this site and produced a wiring diagram that works in the rather odd shed but is as simple as possible. I would be very grateful if someone with a bit of experience could cast their eye over it and confirm it is safe. I attach the diagram. Many thanks in advance.

Rockingit · Dec 17, 2020

The basis seems fine, although I'm thinking it's a bit messy in terms of layout - you'll have a bunch of SFU's that probably don't need to be there.

If you used 4mm cable to spur off from the main house you install a cheap garage CU and just have a 16A MCB fed radial for your sockets and a standard 6A lighting circuit.

Andrew32 · Dec 17, 2020

Rockingit said:
The basis seems fine, although I'm thinking it's a bit messy in terms of layout - you'll have a bunch of SFU's that probably don't need to be there.

If you used 4mm cable to spur off from the main house you install a cheap garage CU and just have a 16A MCB fed radial for your sockets and a standard 6A lighting circuit.

Thanks for the comments: I will check the suggestions out.

Rockingit · Dec 18, 2020

Andrew32 said:
Thanks for the comments: I will check the suggestions out.

NB - I'm making a rash assumption here that the original house ring that will feed the spur has 30mA RCD protection already - otherwise you DEFINITELY need to look at a garage CU with an RCD.

However....... it's also just occurred to me that if you install a consumer unit, irrespective of it being fed via a spur, then it's probably notifiable work under Part P (others may correct me on that). @telectrix @Strima ??

Andrew32 · Dec 18, 2020

Rockingit said:
NB - I'm making a rash assumption here that the original house ring that will feed the spur has 30mA RCD protection already - otherwise you DEFINITELY need to look at a garage CU with an RCD.

However....... it's also just occurred to me that if you install a consumer unit, irrespective of it being fed via a spur, then it's probably notifiable work under Part P (others may correct me on that). @telectrix @Strima ??

The house ring doesn't seem to have RCD protection, so looking more likely that I will need to add that.