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surface-mounted SWA – earthing

Former Community Member
Former Community Member
Just trying to find a regulation that states a reason why the armoured metal of surface-mounted SWA needs earthing. Obviously, when buried underground, it does - 522.8.10.  I have read previous posts on this, but the question seems to have remained unanswered.

It would be considered best practice to at least earth the supply end, but best practice is not regulation. And, considering the statement at the end of Chapter 12, could it not be argued that short runs of surface-mounted armoured without earthing are ‘safe’? Where is the risk?

The armour does not meet the definition of an exposed conductive part when neatly terminated so it can not be touched – under what fault conditions could it become live?

SWA conductors are not double insulated, but is the risk any less than conductors in a plastic conduit?

Manufacturer instructions… it could be that they stipulate that the armour needs to be earthed, but where these are not available for review, how can a non-conformity be raised?

I’d appreciate any replies that point to a specific regulation or group of regulations.

Thanks in advance.

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    Thank you for the further clarification.


    If I came upon this installation as described, I would struggle to go worse than C3 and might not code at all. If the cable had been made off into normal conducting glands then C2 would be justified on the basis that a single fault (e.g. something pierces the cable) would present a danger not only at the point of damage, but also at the ends of the cable. 411.3.1.1


    If you are going to invoke manufacturer's instructions, then I think you need to identify them. If they exist for SWA, do they also exist for T&E or singles. I suspect not.


    As for compliance, presumably there is an EIC where the installer has certified it.


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  • 0
    Thank you for the further clarification.


    If I came upon this installation as described, I would struggle to go worse than C3 and might not code at all. If the cable had been made off into normal conducting glands then C2 would be justified on the basis that a single fault (e.g. something pierces the cable) would present a danger not only at the point of damage, but also at the ends of the cable. 411.3.1.1


    If you are going to invoke manufacturer's instructions, then I think you need to identify them. If they exist for SWA, do they also exist for T&E or singles. I suspect not.


    As for compliance, presumably there is an EIC where the installer has certified it.


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