I don't think anyone could really argue that the outer conductors constituted a 'earthed metal sheath' (indeed, with split con, it would be incomplete).
I would suggest that if you argued that with the regulatory bodies governig my part of the industry you would fail!
That might be true, but we were talking specifically about BS7671 compliance. We know that some things permitted by the regs on your side of the cutout/meter would not be acceptable (to BS7671) within an installation - and probably also vice versa.
We have the same requirements for earthed metallic sheaths, so if we are seen to be complying with that - why do you think the same design of cable does ot comply on the customer side of the meter? Don't forget, either, that we are using 3 core cables of the same basic design with 300mm2 cores.
I suppose you could be right, but I personally very much doubt that is what BS7671 intended. For a start, I'm not sure that a number of separate conductors, some of which are individually insulated, actually constitutes 'a sheath' in the mind of BS7671- that does, after all, leave it theoretically possible that one could penetrate the cable with something fine (e,g, a pin, wire, or even a very small screw/drill and hit the centre conductor without coming nto contact with any of the outer conductors.
i
(hint the neutral is bonded to earth)
Whilst it is obviously true that neutral is connected to earth somewhere, I really don't think that one could satisfy BS7671's requirements for 'earthing' (in any context) by connection to the installation's neutral. That means that, in the case of split con, part of the 'metallic sheath' would not be properly 'earthed' in the sense that BS7671 usually means.
I guess that the BS7671 regulation which prohibits this (clearly very different from things 'on your side' is that which forbids CNE conductors within installations. One could not, for example, use straight con within an installation and argue that the outer neutral was fulfilling the function of a CPC.
However, as we discuss so often, there's really no telling what was in the minds of those who wrote the less-than-fully-explicit regulations!
Kind Regards, John.