No need to rewire the 1mm CPC ring - just to understand that there are a few corner case conditions where the cable may not be adequately protected so if a fault of that kind ever occurs, there is a small risk the cable  would then need to be replaced. The fact that there are many miles of it still in service half a century later suggests that the cable death fault is not that common a situation.

What has changed is that we now calculate and know about those corners.

Mike.

mapj1 said:

No need to rewire the 1mm CPC ring -

Not suggesting that is it. At the end of the day the person carrying out a periodic inspection and test is the one who should make the decision of how to code something.

BUT

There are situations, like one example I know of a relative, where the Zs was at the limit (for ADS) because of 2.5/1.0 ... BS 7671 updated and then no longer below the Zs limit (for ADS) ... and also no RCDs

So, in that case, the coding becomes a bit tricky, because you know you can no longer (according to the latest wisdom) provide protection against electric shock for ADS, and there's no additional protection either ... the two non-conformities (no RCD and Zs not quite met) merge into one in the same cause/effect, and perhaps some people might decide C2, others not ?

I recall back when I did inspections that such a circuit would not comply if it was protected by a BS3036 fuse but would comply if protected by a BS3871 or BS60898 mcb. Since when has this changed?

I think there was a very common attitude that only Zs was important when using MCBs - and c.s.a. could be ignored (nothing in BS 7671 itself supported that, but a lot of guidance seemed to make that assumption). Even today saying 1.5mm² c.p.c. is OK on a B32 is a bit dodgy - as the generic energy let-through numbers from BS EN 60898 only seem to agree with that for devices rated braking capacity up to 3kA. For higher fault currents (remember than for the general case we might be looking at anything up to 16kA at the intake) or on paper even sub 3kA fault currents but with higher rated MCBs, there's nothing general on paper to say it's OK. Individual manufacturers of MCBs might well quote lower figures for their products, but that's not something that can really be relied up on in the likes of the OSG unless you can show that it's true for all BS EN 60898 devices.

No doubt many years of UK practice suggest the actual problem is small, but that doesn't really demonstrate BS 7671 compliance.

   - Andy.

"...Definitely doesn't comply with all BS 7671 requirements, but is there any actual (potential) danger? Would it warrant a C2 on an EICR?"

a fair point and a fair question

i'd suggest no, not a C2 ...  but what do other's think ...

Perhaps, then, C3? So it does not conform to the latest edition of BS 7671, but it conformed when installed. If fact, if we didn't have the C3 code, BS 7671 would be retrospective and I don't think that anybody would suggest that it should be so.

I'd be inclined to agree, C3, at least if those were the only concerns, but it may get added to the weight of other things making up a fail depending condition of the rest - in the sense "it already fails on something else and by the way this another thing is also not really right".

Mike.