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Topic Title: Earth Sizing for sub main
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Created On: 15 August 2006 07:23 PM
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 15 August 2006 07:23 PM
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deleted_13AMP

Posts: 12
Joined: 09 April 2006

Hi, Am installing to two flats with meters in a hall cupboard,with regards to each flat I intend to install a 16mm submain as follows,there is 100amp supply, 25mm tails to 63amp switch fuse, then from here 16mm twin and earth to each flat consumer unit. Is the 10mm earth (in the t+e sufficient for the main earth or will a seperate 16mm earth need to be installed? Many thanks
 15 August 2006 07:30 PM
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perspicacious

Posts: 7030
Joined: 18 April 2006

"Is the 10mm earth (in the t+e sufficient for the main earth or will a seperate 16mm earth need to be installed?"

Are you sure 16 mm2 TW/cpc has 10 mm2 cpc? Doesn't it have 6 mm2?

Regards

BOD
 15 August 2006 08:17 PM
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lbelectrics

Posts: 1035
Joined: 26 October 2004

Bod you're right. 6242Y 16mm has 6mm CPC.

I remember an older standard of 16mm T&E that did have a 10mm CPC, and am sorry that it's no longer available. (Made certain bonding requirements easier to satisfy...)

Any idea what type this stuff was ? The CPC was tinned copper I think, and the live conductor insulation may have been XLPE ???


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Regards

Lee
 15 August 2006 08:28 PM
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DOUGIE1000

Posts: 4113
Joined: 13 August 2005

Im prob going over the top, but i would uses 3core 25mm SWA.

Dougie

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Dougie
Power Plus Electrical.co.uk

My mission is to live as long as possible......so far so good!
 15 August 2006 11:41 PM
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peteTLM

Posts: 3082
Joined: 31 March 2005

SWA all the way.
T and E is rubbish at the best of times, as a sub main, i would avoid. 6mm cpc insufficeint IMHO.
P

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry
 15 August 2006 11:44 PM
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ady1

Posts: 762
Joined: 19 April 2005

I would run a 10mm G\Y to be on the safe side from each 63a SFU. I would also fit a main cut out switch to isolate both flats at source.
Regards
Ady

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Resistance is futile.
 16 August 2006 03:35 PM
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deleted_gcottingham

Posts: 59
Joined: 01 October 2005

Dougie

Why use 25mm SWA surely 16mm would be enough with a 63A fuse?

Regards

Graham
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