S.W.A. Armour Earthing.

I am amazed we still have people arguing that the armour should not be Earthed. No one has made any case that it should not be in terms which I can understand. The special case of an SWA which is TN changing to a TT location just needs some care at installation time and should be immediately obvious to any instructed or competent person. Persons trying to do electrical installation work who are not competent are accepting the risk themselves, it is not your job to try to make their actions safe. Underlying this is the measure of what is "competent"? The likelihood of an incompetent person trying to do inspection and test should be zero, the fact that it is not, is not  my or your problem, the need for competence is clear in the Electricity at work regulations and BS7671.


Earthing exposed conductive parts is inherent in BS7671, and the idea of conductive containment which is somehow insulated (perhaps by paint) has never crossed my mind as satisfactory. There is no requirement that armoured cable is actually insulated at all, so we must assume that it is not. Clearly SWA glands are not, and boots are not fixed, and mechanical damage to the sheath is quite likely (that's why we use SWA) so we must assume it is not insulated. If pressed in Court, I am sure my statement would overcome the rest of the excuses which are being made. Lack of Earth to the Armour must be a code C2. It seems simple enough to me. It will always be Earthed with a 4 core 3 phase cable, as the CPC, why should a single-phase domestic be different?

I am amazed we still have people arguing that the armour should not be Earthed. No one has made any case that it should not be in terms which I can understand. The special case of an SWA which is TN changing to a TT location just needs some care at installation time and should be immediately obvious to any instructed or competent person. Persons trying to do electrical installation work who are not competent are accepting the risk themselves, it is not your job to try to make their actions safe. Underlying this is the measure of what is "competent"? The likelihood of an incompetent person trying to do inspection and test should be zero, the fact that it is not, is not  my or your problem, the need for competence is clear in the Electricity at work regulations and BS7671.


Earthing exposed conductive parts is inherent in BS7671, and the idea of conductive containment which is somehow insulated (perhaps by paint) has never crossed my mind as satisfactory. There is no requirement that armoured cable is actually insulated at all, so we must assume that it is not. Clearly SWA glands are not, and boots are not fixed, and mechanical damage to the sheath is quite likely (that's why we use SWA) so we must assume it is not insulated. If pressed in Court, I am sure my statement would overcome the rest of the excuses which are being made. Lack of Earth to the Armour must be a code C2. It seems simple enough to me. It will always be Earthed with a 4 core 3 phase cable, as the CPC, why should a single-phase domestic be different?