How best to wire a new ground floor extension

21 Apr 2010
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United Kingdom
Hi All,

I am looking for some advice on how best to wire a ground floor extension.
Previously there was conservatory which had sockets installed that were spurred off the dining room sockets under the floor. when i removed the conservatory, i removed the sockets and wiring..

Now the new extension is up, i need to run new sockets and lighting, but i am wondering how best to do this. I am not going to do all this myself as building regs says it needs to be Part P signed off, but i can atleast do the dirty work of running cables / conduit and setting up socket locations.

So should i just run the cables back in a ring main extension and feed from and back to the existing sockets in the dining room, or should i run a whole new circuit from the CU to the extension.

The extension will include kitchen appliances such as dishwasher as i am extending the kitchen into this new extension.

Any thoughts on how i should start to set out the electrics?
New ring main from consumer unit or extend dining room (downstairs sockets) into the extension?

Many Thanks
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You're not entirely clear on what the extension is.

If you currently have a dedicated ring for the kitchen, best to extend this into the extension if the extension will form part of a larger kitchen.

If you dont have a dedicated ring for the kitchen, best to provide one, at least for the new part, but preferably incorporating the old part too.

Lighting - depends how heavily loaded the circuit is already, and what you intend to add.

Under part P you CAN do the work yourself.

// p
Thanks Steve,

the extension is a full rear brick extension which will have the existing kitchen and dining room extended into it. I currently only have a fuse for ALL of the downstairs sockets, so i assume its a single ring main for the downstairs.

I need to lift floors up in the exisiting kitchen anyway for pipes etc, so thought i could just as easy run wiring for a new ring main to the new extension, but i like the idea of having a new ring main for the extension and inc the old kitchen. that could work...

Can i really do this myself? i thought i wasnt allowed to run new circuits?
Dont i also need to get the whole house electrics tested as part of building control sign off?

Thanks again for your quick reply.
Run a 20A radial for the kitchen appliances, and another one for the rest of the new sockets.

Don't faff about with ring final circuits - bad design and makes things difficult to extend/add in the future.
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If you are looking to get an electrician to sign it off for you, you may have problems as we're not allowed to sign off work we've not installed. I would advise getting one in as soon as possible and agreeing with him/her how much of the legwork you can do.

Run a 20A radial for the kitchen appliances, and another one for the rest of the new sockets.


That's bad design as a kitchen could exceed 20A - think wash m/c, dishwasher, tumble drier, toaster, microwave, kettle...............

Yes it would, but the OP hinted that only some appliances would be on this circuit, therefore I recommended a 20A circuit for the dishwasher that the OP mentioned.

Of course, s/he would have to evaluate loading requirements before deciding upon a design.

Loads of appliances on a 'traditional' 32A/2.5mm^2 ring final is not good either.
Under part P you CAN do the work yourself.

// p
Sadly, the practical reality when there is an extension involved is that he's going to have to go along with what his particular council have chosen to do regarding DIY electrical work.

If they are one of the ones who, albeit unlawfully, say that they expect the applicant to also provide an EIC from a qualified electrician, then a stand-up fight with them or recourse to legal action, or just telling them to stuff their notification could put the whole sign-off of the extension at risk.

Plus there's the sneaky way that many councils try to trick people by telling them that on their application for Building Regulations approval they must say that the electrical work will be done by a registered electrician...

smilerbatten - this is important, as it may seriously limit your options - when you applied for BR approval, what did you say would be the way that you'd comply with Part P?

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