Additional Consumer unit 20M away.

[dw3101]

If im addding an addtional consumer unit in a garage (attached to the hosuse) to provide circuits for a proposed extension and also for a new kitchen,

so:

They specified 2x32a supplys for Hob and Oven. :O
Lighting 6a
Kitchen Ring 32a
Extension Ring 32a
Spare 32a

So was thinking a sixway metal clad consumer unit to go on the garage wall, I would run new cables to the existing CU but there is insufficient room there and also the house will be decorated prior to the building works.

I was thinking SWA as I have only seen up to 16mm T&E

Would you fit a 63A DP isolator instead of the 100A in the Garage CU?

There is a Henley block allready installed so was going to fit a DP Isolator / CU at the Consumer unit end with 25mm meter tails to the henley block. Earthing will be provided by the armour and also a spare core. (PME installation)

What size SWA would you use, as Im sure the modern supply cables arent overly big?

I suppose diversity needs to play a part here too.

Thanks in advance.

David

 

[ban-all-sheds]

Unless you want the mechanical protection, 16mm T/E on a 63A switchfuse to feed the new CU would be OK. If you want SWA, 10mm XLPE will be fine.

I'd look more closely at the cooker circuits - it's unusual for an oven to need 32A - often they can just plug into a socket. But even if not, you might find that 45A for the hob and 20A for the oven is a better split.

Don't forget you'll want the rings but not the cooker circuits or lights with RCD protection, so your new CU should be a split-load one. And if there's a fridge-freezer involved, lay in a non-RCD circuit for that as well.

 

[plugwash]

you shouldn't run more that a short distance from the meter withotu your own isolation and overcurrent protection

what are the power ratings of the hob and oven?

the official diversity rules are frankly a bit of a farce on domestic installs always giving figures much higher than any normal domestic service fuse but if you are not using much direct electric heating i think a 50A cuircuit will easilly cover it

i would start from a 50A or 63A breaker in the non-rcd side of the main CU and run from here in 16mm T&E to your new CU which should really be a split board so the lighting can be kept on non-rcd

 

[dw3101]

Good point about the split load I had overlooked that..

Its the kitchen fitters that had specified that.. dont get me started on kitchen fitters.. Ill get the home owner to check, doing this as a favour as they were going to be doing it, along with the builders.

Can you get bigger than 16mm T&E.. only ever used 10mm and thats bad enough to work with Is the current carrying capacity different between T&E & SWA??

I dont need mechanical protection, but seemed like a good idea as its going to be surface mount / conduit and then under the floor in the landing / hall area upstairs..

David

 

[dw3101]

Plugwash,

I said I was going to fit either a small CU or a DP Isolator..

Depends on cable used as having never purchased an 'isolator' I dont know whether it would take a cable gland.

David

 

[plugwash]

a small CU from henly blocks is an option if you have no space in the non rcd side of your existing CU

63A is the largest rating you can get in a normal sized mcb (and i think quite a few brands stop at 50A) and 16mm T&E will be fine on this

you are suppsed to have your own overcurrent protection so an isolator alone is not ok

frankly i think a 50A cuircuit will be fine and a 63A cuircuit will be ample

if you want larger than 63A you basically move into switchfuse territory and theese are definately designed to be used with swa glands

note that if your box doesn't come with the right size knockouts for the cable gland needed for your size of cable you will need to buy a holesaw

one final thing the new CU should be clearly labeled as a sub board so that people in the future don't get the idea it isolates the whole house

 

[dw3101]

No probs.. Good point about the isolator.. however I would have realised that when it came to installation, allways easier when its in your had and you can see it!

Ill get a price for some 16mm T&E from the local wholesalers in Leeds.

David

 

[ban-all-sheds]

you shouldn't run more that a short distance from the meter withotu your own isolation and overcurrent protection

That's what I said....

what are the power ratings of the hob and oven?

That's what I suggested he check....

[/quote]i would start from a 50A or 63A breaker in the non-rcd side of the main CU and run from here in 16mm T&E to your new CU which should really be a split board so the lighting can be kept on non-rcd[/quote]
I always think it's neater to supply a second CU directly from the meter tails via an isolator + MCB or a switchfuse....

 

[plugwash]

i somtimes answer queires without fully reading previous ones

anyway i think between us he got it

 

[dw3101]

Just wanted to run it by people in the trade, Im going to see what he wants in the way of expansion / capacity..

Will have to go to massive cable if he plans for electric showers etc.

David

 

[Lectrician]

25mm split con on a 63 or 80amp sw fuse, 25mm tails to henly. Split board in garage.

If running under floors, split concentric is fine, and thes best bet (just like t+e only different ).

Thats my view.

 

[dw3101]

got any links to split concentric?

Any ideas on cost per m?

 

[ban-all-sheds]

This technique is a good habit to get into when looking for things:

http://uk.altavista.com/web/results?itag=wrx&q="split+concentric"&kgs=1&kls=0

 

[bd2e]

Hello, I'm new to these forums so just browsing at the moment. I hope you don't mind me asking but ban-all-sheds said in an earlier post

<quote>Don't forget you'll want the rings but not the cooker circuits or lights with RCD protection, so your new CU should be a split-load one. And if there's a fridge-freezer involved, lay in a non-RCD circuit for that as well.<unquote>

And I wondered why the cooker circuits should be on the non-RCD side of the CU?

Thanks

 

[ban-all-sheds]

Cooker elements are prone to getting damp in them. No danger - it evaporates almost immediately, but can trip RCDs.