Extension wiring

Hello

We are building an extension to a average 3 bed semi-detached. The extension is downstairs side and back, (extension of kitchen + some other rooms).

I will be doing the wiring and having BC do the relevant testing and inspection for Part P purposes.

The house was rewired in the late 90s before we acquired the house.

Currently the wiring is split by lighting upstairs, lighting downstairs, sockets up, sockets down, (plus some others).

What is normal practice for an extension like this, is it to extend the existing circuits (lighting and sockets) or to add a new circuit for each of the lighting and sockets?

Normal practice is to design according to your preferences, subject to engineering and legal requirements.

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It depends on the loading of the existing circuits really.

If you have an independent ring circuit supplying just the existing kitchen sockets, then you may want to extend this to include the extension kitchen. And then you could extend the 'rooms' ring to include the 'rooms' extension.

Ring circuits aren't meant to exceed an area of 100 square metres.

If you only have one ring circuit it may pay to add a new ring.

It all depends on the layout of the house and extension, and to some extent the size of the extension.

Generally, the main problem with extending a lighting circuit would be overloading it. Have no idea how many lights/what type of lights you will be adding. Some new lights may need to come on together with the old ones possibly, so that has to be considered.

If it's only a small extension it may not be worth running in new circuits; however, it may be very sensible to do so.

More info required.

Would be worth getting a professional in to look, and probably best to let him do the whole job.