Well trodden debate in terms of say hot tubs or outbuildings where the origin is a TN-C-S, the general consensus rightly or wrongly is to not “export” the PME to the load side and instead “TT” it. However when the supply is via an SWA cable this raises the issue of the armour/glands becoming an extraneous conductive part and potentially introducing touch voltage risk outdoors.
it seems to be commonplace to earth the armour at the supply end and then use stuffing glands or other means at the “TT” end to keep the PME earth isolated from the TT electrode earth and final circuits/load.
Is it not logical to earth the armour from the TT earth and isolate at the supply end in similar fashion with stuffing gland etc therefore there is no risk from either touch voltage or lost PEN scenario causing the armour to become live ?
I can see there is a problem in protecting the SWA cable by ADS in this manner but the use of an RCD providing fault protection for the SWA would be no different than a TT supply is from the DNO ?
it seems to be commonplace to earth the armour at the supply end and then use stuffing glands or other means at the “TT” end to keep the PME earth isolated from the TT electrode earth and final circuits/load.
Is it not logical to earth the armour from the TT earth and isolate at the supply end in similar fashion with stuffing gland etc therefore there is no risk from either touch voltage or lost PEN scenario causing the armour to become live ?
I can see there is a problem in protecting the SWA cable by ADS in this manner but the use of an RCD providing fault protection for the SWA would be no different than a TT supply is from the DNO ?