Garage/room extension wiring questions

Hi there,

I’ve just had a garage and room extension built and it’s now ready for the first fix and I’m after your advice on some electrical wiring questions please.

1. Can I run wires in myself? This is just to try and save money obviously I’ll need it testing to part P and passing off. (I’m an electrician but work on aircraft, educated (1993) to the IEE 16th edition. I’m not JIB registered.)

2. My consumer unit is in my kitchen, and I plan on passing the cables through the wall into the new garage, wiring the garage then passing the cables through another wall into the new room at the back of the house. What’s best to pass these cables through the walls, should they be in conduit?

3. The garage is going to be wired in PVC conduit and metal clad boxes, in single cores. Can I continue the ring main from the garage into the new room at the back but changing to twin and earth cable in the room, via a junction box’s? Am I right in thinking this is now not allowed?

4. Switch drops in the room are going to be behind plaster board, these have to be in some kind of mechanical protection like a PVC channel, is this also the case for horizontal cable?

Thanks

Andy

It will all depend what was put on your application to LABC. If you have said your doing electrics then likely covered in fee paid. But if they expected a registered electrician they may want a further fee.

At £100 plus council fee the cheap option will depend on if you have to pay extra fee or not.

There is no real reason why a ring should be limited to garage. There is a max area covered but you are unlikely to exceed that.

Since you have the skill I would consider mineral cable in a garage. Depending on area and availability the new Ali-tube to BS 8436 has good protection both physical and fire and if you don't like mineral cable this looks like mineral and dresses well. If you have ever tried pulling twin and earth through plastic conduit you will realise not best option and with singles really no better protection than plain twin and earth and clips.

ericmark said:

Since you have the skill I would consider mineral cable in a garage

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I would consider it everywhere.

You can fit wires and any other electrical items yourself, provided you notify LABC before starting. Since this is a new extension, it should have been notified already.

Cables through walls - they can go straight through the wall, however using conduit is a good idea, particularly if there is a cavity in the wall.

Junction boxes are allowed, provided they are accessible. Joining the cables in the back of a socket would be a better option.
For the other room, why not just continue with the PVC conduit and singles?

Switch drops and other cables in the wall do not need mechanical protection provided they are RCD protected and are in 'safe zones' such as directly above, below or horizontally in line with a switch or socket. PVC channel is not mechanical protection anyway, a nail will go through it easily.

Thanks for your response.

much appreciated

I’ll need it testing to part P and passing off.

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Firstly, there is no Part P test.

You have to comply with Building Regulations. One way of complying with Part P is to carry out the wiring to BS7671.

If you plan to do it yourself, you'll need to carry out the testing etc using calibrated test equipment and do the certification.

If you plan to use a registered electrician, he/she will be signing it off as work they have done themselves so they will want to be involved, from the start. You wont get anyone to sign it off later!

Aah, plumbers. The little treasures!

That particular one should be buried