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Topic Title: main protective conductor
Topic Summary: SWA cable
Created On: 25 June 2012 12:00 PM
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 25 June 2012 12:00 PM
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Maca1170

Posts: 2
Joined: 25 June 2012

I have a 4 core 2.5 cable, 3phase earth running out to an isolator.
The SWA has a CSA of 20mm but is only the equivalent of a 6.43mm
The regs say thew minimum CSA of a main protective bonding condutor should be no less than 10mm square.
Can I use the SWA as my main protective conductor.

I also have 3 seperate SWA cable running to the same isolator can I combine all 4 SWA and use it as my main protective bonding conductor. or do I need to run out a seperate earth cable.
 25 June 2012 12:39 PM
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weirdbeard

Posts: 1456
Joined: 26 September 2011

Hi, could you explain a bit clearer what you are trying to achieve, ie: where you already have a 2.5mm core and presumably the armour of the swa currently connected as the c.p.c, what is the reason that you need sufficient csa to use these connections as a main protective bonding conductor - will you be connecting from this isolator to extraneous conductive parts?
 25 June 2012 02:13 PM
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Jobbo

Posts: 912
Joined: 08 July 2010

Maca

Your equivalent 6.43mm2 is only applicable if used as a cpc not bonding conductor. The copper equivalent is approximately 2.5mm2

Regards

Jobbo
 25 June 2012 04:22 PM
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aligarjon

Posts: 2802
Joined: 09 September 2005

i can't see how you can use multiple cables to make up a main bonding CSA. there is the obvious and likely possibility that some of them might get removed or altered at some point in the future.

Gary

-------------------------
Specialised Subject. The Bleedin Obvious. John Cleese
 25 June 2012 04:48 PM
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OMS

Posts: 19463
Joined: 23 March 2004

Safety label in accordance 514.13.1 ?

Maybe not -

OMS

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Failure is always an option
 26 June 2012 12:29 AM
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stableford

Posts: 64
Joined: 04 April 2006

If the load is a motor on a VFD, then run a separate bonding conductor, as the SWA would be a screen, for the VFD noise in the cable, and the bonding conductor becomes the functional earth.

Best document for cabling a VFD is an ABB drive manual.

Regards

Derrick
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