Am I correct in thinking that metal kopex is not suitable for use as a CPC, therefore can not be used to run cables outside the prescribed safe zones?
The reg does indeed say that ... but what if the cable within has an acceptable 'protective conductor' (CPC) and the flexible conduit is being used only as an outer earthed 'protective covering'?543.2.3 says flexible conduit cannot be used as protective conductor so I would say you are correct.
It won't be reliably earthed though, which is precisely why it can't be used as a cpc.The reg does indeed say that ... but what if the cable within has an acceptable 'protective conductor' (CPC) and the flexible conduit is being used only as an outer earthed 'protective covering'?
Kind Regards, John
Yes, but as I said, what if it's not being used as a CPC?It won't be reliably earthed though, which is precisely why it can't be used as a cpc.
So it does! QED, then.522.6.204(i) says only a metallic covering which does meet the requirements of a CPC of the circuit comply.
Indeed. I suppose it does rather beg the question as to what that sort of flexible conduit is actually useful for - I suppose only if it is 'exposed' and being used to provide a bit of mechanical protection?Thanks. I found the regs quoted above after I posted the question so we all agree
Presumably you earth it? How easy is it to get a 'reliable' electrical connection to it, and how does one do that - does it perhaps come with some sort of 'glands'? (you can tell that I've never used the stuff!)Yes we use it a lot to supply motors, limit switches and anything like that which needs a bit of tolerance to movement. It's not as tough as rigid steel, but it's fine in the right environments, and more resistant to impact, fauna etc than PVC.
Thanks. Not that much different from the plastic 'glands' I have used for flexible PVC conduit, which I've occasionally used just to reduce the risk of 'abrasion damage' in places like garages and cellars!You use a gland like this. The coarse thread screws inside the kopex, and the other side is a standard M20 thread.
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