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surface-mounted SWA – earthing

Former Community Member over 3 years ago

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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0 Former Community Member over 3 years ago

Replying to previous posts - This is the point of my OP.

I’ve googled SWA data sheets but not found anything to say the steel ‘must be earthed’, but equally, I’ve not found any literature – anywhere - supporting no earth…

Where SWA is a requirement, you would expect the steel to be earthed, but in this scenario, the steel is surplus to requirements hence the installer's method of termination. Would a manufacturer support this method? I doubt it.

To be honest, I don’t have an issue with it, but I have been tasked with approving the installation after another electrician has already condemned the lack of earth – so the issue needs to be resolved. I feel, on this occasion, that it would not be unreasonable for me to ask the installer to prove compliance rather than me disprove.

I’ll probably word the nc something along the lines of “ It is unlikely that the SWA cable manufacturer would support an installation where the steel armour is not earthed…”

Btw – domestic – through cavity wall to outside.
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0 Former Community Member over 3 years ago

Replying to previous posts - This is the point of my OP.

I’ve googled SWA data sheets but not found anything to say the steel ‘must be earthed’, but equally, I’ve not found any literature – anywhere - supporting no earth…

Where SWA is a requirement, you would expect the steel to be earthed, but in this scenario, the steel is surplus to requirements hence the installer's method of termination. Would a manufacturer support this method? I doubt it.

To be honest, I don’t have an issue with it, but I have been tasked with approving the installation after another electrician has already condemned the lack of earth – so the issue needs to be resolved. I feel, on this occasion, that it would not be unreasonable for me to ask the installer to prove compliance rather than me disprove.

I’ll probably word the nc something along the lines of “ It is unlikely that the SWA cable manufacturer would support an installation where the steel armour is not earthed…”

Btw – domestic – through cavity wall to outside.
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surface-mounted SWA – earthing

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