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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
    This discussion has gone on for a long time. In an EICR, if everything is fully insulated I would give a C3. It is not a standard method and it requires improvement. It is only potentially dangerous if the cable is damaged sufficiently to expose the armour, and connect it to a live conductor, which is very unlikely. The "other" electrician has condemned it, presumably on the basis of an exposed conductive part as my previous post, but if it is all mechanically protected, similar to a sheathed cable, it is not immediately dangerous, unless as the previous sentence. In my opinion, SWA with unconnected armour is simply bad workmanship, there is no sense in not Earthing it, and the EVSE install mentioned by Lyle is simply perverse. From the OP, write out an EICR form, only covering this cable on the limitations section, code it a C3 referring to 411 and give it to the client. His problem, he can get it fixed or not, you have provided a report in place of certification, everyone should be happy.
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  • 0
    This discussion has gone on for a long time. In an EICR, if everything is fully insulated I would give a C3. It is not a standard method and it requires improvement. It is only potentially dangerous if the cable is damaged sufficiently to expose the armour, and connect it to a live conductor, which is very unlikely. The "other" electrician has condemned it, presumably on the basis of an exposed conductive part as my previous post, but if it is all mechanically protected, similar to a sheathed cable, it is not immediately dangerous, unless as the previous sentence. In my opinion, SWA with unconnected armour is simply bad workmanship, there is no sense in not Earthing it, and the EVSE install mentioned by Lyle is simply perverse. From the OP, write out an EICR form, only covering this cable on the limitations section, code it a C3 referring to 411 and give it to the client. His problem, he can get it fixed or not, you have provided a report in place of certification, everyone should be happy.
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