Moving CU and connecting an additional one

[DaveS]

As part of some house extension work I want to move the main CU from the garage to a new room (part of the extension) and add a garage CU. The gge CU will be feeding a 3kW rotary 3 phase converter (from class D MCB) and a 2kW 3 phase inverter in addition to the ring and lighting.

Questions:
- are the tails allowed to run horizontally through the wall from the gge into the back of the CU?
- do I have to run the tails to the gge CU from a MCB in the main CU or can I wire them in parallel with the main CU tails?
- the tail length to the main CU will be about 2 metres, what XSA is recommended (100A main fuse)?
- can I run the cables from the new CU horizontally through the wall from the gge into the back of the CU?

DaveS

 

[fubar]

Are you a sparky and do you have an isolator switch between CU and mater (and I don't mean in the CU)?

 

[ban-all-sheds]

Are you a sparky and do you have an isolator switch between CU and mater

Do not connect your mum to the mains, with or without an isolation switch...

 

[DaveS]

I'm a sparky of sorts (Electronics degree) and am happy and experienced at working on house wiring but I don't know the current rules - hence the questions.

There isn't a meter-CU isolator at the moment but it might be a good idea, does it HAVE to be fitted in the meter cupboard (external) or can it be next to the CU (for example)?

When I rewired my Mum's flat (a long time ago) I broke the seal on the Henley block and pulled the main fuse; I rang the local elec company and they were happy to come out and re-seal without charge. Is there any reason not to do the same?
If I need to replace the tails I would need to break the meter seal too, would that change the answer?

BTW, I just saw that I typed "diameter" when I meant XSA.

DaveS

 

[ban-all-sheds]

BTW, I just saw that I typed "diameter" when I meant XSA.

 

[DaveS]

Thks ban-all-sheds, didn't notice the edit option.

 

[Spunky]

I'd put the switch near your CU mate for ease when working on it.

 

[ban-all-sheds]

I'm a sparky of sorts (Electronics degree)

That doesn't make you a sparky of any sorts. I'm not one, and I'm not agitated at what you wrote, but I should warn you that you might get a bit of abuse over that.

There isn't a meter-CU isolator at the moment but it might be a good idea, does it HAVE to be fitted in the meter cupboard (external) or can it be next to the CU (for example)?

AIUI, if it's your switch it can't be in the meter cupboard, as that isn't "yours" (even if you paid for it). And anyway, you don't want it out there...

When I rewired my Mum's flat (a long time ago) I broke the seal on the Henley block and pulled the main fuse; I rang the local elec company and they were happy to come out and re-seal without charge. Is there any reason not to do the same?

Yes - these days it might not be free and they might ask for a certificate for your installation. Of course you should be advised not to pull the fuse, but if you choose to ignore that advice it would be best just to do it and say nothing to the DNO.

If I need to replace the tails I would need to break the meter seal too, would that change the answer?

I believe they can get more agitated about the meter seals, but if you wanted to steal electricity you could just as well do it by breaking the fuse seal. Another point is that the tails are not yours... If you can justify a tails upgrade, then you probably should get the DNO to do it. Get your iso switch in place, and the tails for that, and when the engineer comes to do the DNO tails, give him a bung to wire in the switch..

 

[securespark]

Call yourself a spark? ELECTRONICS DEGREE????? Pah! You must be kidding! You can't do a degree in electronics and think you know it all!

Just providing "a bit of abuse" that Ban predicted.

To upgrade your electronics degree to a fully qualified Electrician, you first of all need a phD in Builders Bum, and a C & G 2397 in sucking air through your teeth while simultaneously shaking your head. A refresher course in Brewing would be helpful.

Who said blokes can't multi-task?

 

[DaveS]

OK, I'm suitably chastised but I had some pretty big sparks (and bangs) when I worked on EHT and power systems.