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


 25 June 2012 04:22 PM
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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.


Specialised Subject. The Bleedin Obvious. John Cleese
 25 June 2012 04:48 PM
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Safety label in accordance 514.13.1 ?

Maybe not -


Let the wind blow you, across a big floor.
 26 June 2012 12:29 AM
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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.



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