Powering a garden room

[adelast]

Hi everyone,

I'm planning to building a garden office next year and as usual, I'd like to plan as much as I can :).
Currently, we have a small brick shed where our washing machine is located. The idea is to demolish that and build a garden room bigger, cleaner and with the right amount of ventilation.
I have some questions regarding the electrical that it will require. When we bough the house 2 years ago, there was already a connection between the house and the small shed. This seems to be a spur, coming from the inside of the house, on top of the garden backdoor and then directly into the shed.

Now, I know that a single spur won't suits my needs, however I was wondering, since the garden room and the house will be less than 1 meter apart, can I extend the internal existing ring circuit to the garden room? That would avoid the need of bringing power from the front of the house (where the consumer unit is), remove all the slabs, dig etc etc.

I am attaching a picture of current setup, to clarify what I have right now. Would it be within regs passing the cables on the top instead of underground?
I have experience on adding extra sockets within a ring circuit and I feel like I can do that, however if this would be out of regs and power from the main consumer unit is needed I'll call a pro. I just want to be sure that is the only option, cause dig for the cable from the front of the house will make this a huge job.
Thank you for your input!

[Neelix]

FWIW I wouldn’t extend a ring to an out building, so my advice to you is get a local spark to take a look at the practicalities of a dedicated circuit and small fuseboard in the cabin

[ericmark]

A ring final has a maximum length, often quoted as 106 meters, this is length of wire so includes going up/down walls. It is easy to exceed the limits. We should measure the R1 + R2 etc, before we add to a ring final, and to be frank DIY we simply don't have the meters required, so since your going to have a high load, really not a DIY job.

[adelast]

Thank you both for your replies!
I'll review the regulations to understand if there's an alternative to digging into the concrete & slabs to carry the electricity from the front to the back. It's too soon to call a pro as we will build it next summer

[Neelix]

There’s nothing wrong with the submain running around the side of the house ….higher up

[adelast]

Oh that's good news, what diameter would this cable have normally? I know the cables inside are wrapped in a ticker plastic and a kind of metal mesh

[ericmark]

Mineral insulated cable can be quite thin, but not a DIY job. There are likely many ways around the problem, but need reading to work it out.

To swap a scoket for a fuse and add more sockets is easy, but to extend a circuit you need to know what is already there.

[adelast]

Thank you, I thought the cables were a lot bigger than that. I believe I will be able to have the electrician passing them at the very bottom of the walls along the perimeter, hidden below the timber where the downlight are.

Thank all for your input