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Topic Title: Sub mains ran under staircase
Topic Summary: Acceptable
Created On: 22 January 2013 09:32 PM
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 22 January 2013 09:32 PM
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ady1

Posts: 766
Joined: 19 April 2005

Can a sub main be ran using the same methods etc as an ordinary circuit? It's 16mm T&E with an additional 10mm earth - or are there any additional requirements, as its to supply a board?
Yes - I want to run it in a void below a staircase ?

Regards
Ady

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Resistance is futile.
 22 January 2013 09:37 PM
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peteTLM

Posts: 3217
Joined: 31 March 2005

Is this buried in the wall or surface?

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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
 22 January 2013 09:38 PM
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AJJewsbury

Posts: 11699
Joined: 13 August 2003

Can a sub main be ran using the same methods etc as an ordinary circuit?

Yup, BS 7671 makes little distinction between circuit types (the only one that comes to mind is disconnection times). If it's concealed <50mm deep in a wall anywhere along its length then it'll need 30mA RCD additional protection too.
- Andy.
 22 January 2013 10:08 PM
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ady1

Posts: 766
Joined: 19 April 2005

Hi Andy/Pete
That's why the void under a boxed stairs and then trunken, is preferred, as I don't want to RCD the sub run.
So, no, its not buried in the wall.
I guess the main question is, do we feel its acceptable to run a sub main cable in a void created under and around a staircase ?

Regards
Ady

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Resistance is futile.
 23 January 2013 09:19 AM
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Ricicle

Posts: 850
Joined: 23 October 2006

No different to a CU under the stairs with all the final circuits eminating from there in some form of boxing.

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Empty barrels make the most noise.
 23 January 2013 06:46 PM
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peteTLM

Posts: 3217
Joined: 31 March 2005

Id personally prefer a bit of swa as a submain, but i guess it depends on the environment and length of run.

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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
 23 January 2013 07:02 PM
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aligarjon

Posts: 2901
Joined: 09 September 2005

Originally posted by: ady1

Hi Andy/Pete

That's why the void under a boxed stairs and then trunken, is preferred, as I don't want to RCD the sub run.

So, no, its not buried in the wall.

I guess the main question is, do we feel its acceptable to run a sub main cable in a void created under and around a staircase ?



Regards

Ady


so long as the cable is 50mm from the surface of the void. Are we talking about down the back of the treads here, if so i would think it very difficult to achieve unless its clearly defined as a cable enclosure.

Gary

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Specialised Subject. The Bleedin Obvious. John Cleese
 23 January 2013 07:13 PM
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peteTLM

Posts: 3217
Joined: 31 March 2005

Originally posted by: aligarjon

Originally posted by: ady1



Hi Andy/Pete



That's why the void under a boxed stairs and then trunken, is preferred, as I don't want to RCD the sub run.



So, no, its not buried in the wall.



I guess the main question is, do we feel its acceptable to run a sub main cable in a void created under and around a staircase ?







Regards



Ady




so long as the cable is 50mm from the surface of the void. Are we talking about down the back of the treads here, if so i would think it very difficult to achieve unless its clearly defined as a cable enclosure.



Gary


i dont see it as being any different from floorboards, and we dont go round banging 6'' nails into floors or staircases do we?

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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
 23 January 2013 07:26 PM
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aligarjon

Posts: 2901
Joined: 09 September 2005

Maybe Pete. although i was always taught to clip cables 4 inches up the joist and down from the top. i don't know whether thats in the regs or not or just good practice / common sense. ?

Gary

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Specialised Subject. The Bleedin Obvious. John Cleese
 23 January 2013 07:36 PM
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Avatar for OMS.
OMS

Posts: 19861
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although i was always taught to clip cables 4 inches up the joist and down from the top. i don't know whether thats in the regs or not or just good practice / common sense. ?


Pretty much what I was taught - clip along the approx centre line of the joist (because that's where drilling holes in the joist has the least structural impact) essentially.

regards

OMS

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 23 January 2013 07:48 PM
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peteTLM

Posts: 3217
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i was thinking more along the lines of old school notches in joists where the cables (and pipes) have the potential to be pushed up to the underside of the floor, ruling out anything more than a carpet tack banged into the floor.

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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
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