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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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    Sparkingchip:
    Chris Pearson:

    If the cable is surface mounted, AND a core is being used as the CPC, AND the cable is neatly terminated into enclosures with insulating glands, then I agree that there are no ECPs, so the armour does not have to be earthed.

     


    So you completely disagree with the extract from the IET Guidance Note 8 which I posted?




    Yes, because exposed-conductive-part = conductive part of equipment which can be touched ... .


    I cannot think of any circumstances when you would specify SWA, but not use it as intended, but that wasn't the issue in the OP.


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  • 0
    Sparkingchip:
    Chris Pearson:

    If the cable is surface mounted, AND a core is being used as the CPC, AND the cable is neatly terminated into enclosures with insulating glands, then I agree that there are no ECPs, so the armour does not have to be earthed.

     


    So you completely disagree with the extract from the IET Guidance Note 8 which I posted?




    Yes, because exposed-conductive-part = conductive part of equipment which can be touched ... .


    I cannot think of any circumstances when you would specify SWA, but not use it as intended, but that wasn't the issue in the OP.


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