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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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  • 0
    It’s easy to find guidance telling electricians to earth the armour of SWA cables, such as this:

     

    Providing automatic disconnection of supply (ADS)



    Regardless of whether the armouring of the cable serves as a protective conductor, or not, it should always be effectively earthed to ensure the requirements of ADS are met. Should the armouring not be effectively earthed and a fault develops due, for example, to mechanical damage of a line conductor incorporated in the cable, the condition may leave the armouring attaining line voltage and pose a danger to persons in the vicinity of the installation or using the installation.

    https://www.voltimum.co.uk/articles/guide-installing-steel-wired-armoured


    Can anyone post a link to what seems to be an authoritative article saying that it’s not required? There’s plenty of “how to do it” videos on Youtube in which electricians say it’s not required, but I don’t count consider those authoritative. 


     


Reply
  • 0
    It’s easy to find guidance telling electricians to earth the armour of SWA cables, such as this:

     

    Providing automatic disconnection of supply (ADS)



    Regardless of whether the armouring of the cable serves as a protective conductor, or not, it should always be effectively earthed to ensure the requirements of ADS are met. Should the armouring not be effectively earthed and a fault develops due, for example, to mechanical damage of a line conductor incorporated in the cable, the condition may leave the armouring attaining line voltage and pose a danger to persons in the vicinity of the installation or using the installation.

    https://www.voltimum.co.uk/articles/guide-installing-steel-wired-armoured


    Can anyone post a link to what seems to be an authoritative article saying that it’s not required? There’s plenty of “how to do it” videos on Youtube in which electricians say it’s not required, but I don’t count consider those authoritative. 


     


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