I'd say "needs improvement". A single 2.5mm T&E is already rated to 27A for clipped direct, and we already allow single-cabled spurs. So I think the likelihood of a single CPC melting during a fault is low.

A discontinuous c.p.c. on a ring raises a number of questions - how has it come about? A loose connection somewhere (in which case there might be a point somewhere, if hidden, without an adequate earth, unless the accessory had dual earth terminals), or a damaged cable might be indicative of much more serious problems (e.g exposed live parts - even if they don't happen to show on an insulation test). Without further information it might have to be an FI. Then there's section 543.7 - if the circuit could have protective conductor currents >10mA then a further single fault (another break in the c.p.c.) could lead to shocks from exposed-conductive-parts - shocks from a single fault is a C2 in my book. I'd consider a C3 if I was happy that it wasn't a symptom of anything more serious.

Lack of additional protection by 30mA RCD again depends - for sockets serving indoor equipment I'd say C3, but if intended to serve outdoor equipment then a C2. Likewise for bathroom circuits C3 if there's the equivalent of supplementary bonding (either actual supplementary bonding or a combination of c.p.c.s/main bonds that have the required effect) or C2 otherwise.

   - Andy.

BPG4 Issue 6 lists this as C2 (page 17) plain and simple because of the discontinuous cpc.

Whilst Zs may be OK for disconnection time, you've provided no further information regards csa and type of OCPD, so the thermal effects is still open to question.

Most importantly,  the discontinuous cpc doesn't meet the requirements for protective conductor of an RFC of Regulation 543.2.9 (except if the RFC in its entirety is enclosed in continuos metallic containment that is also used as the cpc for the RFC ... but then it won't be discontinuous?).

 sorry - a reader should not be asked to presume [too much :-)]  ... so ...   'presume' a standard domestic 2.5/1.5 t&e rfc circuit on a 32A B MCB    with and without 30mA RCD with let's say nominal 0.45 end to end L & N

having said that  Andy has raised some other good points (hidden things and so on).

interestingly i asked this question many moons ago and at the time it was determined that with all accessible accessories presenting earthed with Zs good etc,   ...    some said that it might/should be only C3   whilst others C2 no doubt   (as in potentially dangerous)    ....      

regards

At the end of the day, the person undertaking the periodic verification is the only person who has seen that particular installation, and it is up to them to make the assessment based on what they have see in that installation alone.

The points we raise here (and the point made in guidance) are, to be fair, only points the person undertaking the periodic verification can take into account in making their decision.

There is no one-size-fits-all answer, experience and attention to detail are key competences for the person undertaking the periodic verification.

How can there be a satisfactory Zs when there is no CPC. "Discontinuous CPC" to my mind = no CPC.

However, if you mean that only one CPC is connected to the MET, I would say FI. (Or C2, which amounts to the same thing.) Somebody needs to inspect the rest of the ring and find the poor connection.

of course as acknowledged and is a given.

with respect though, if that's all a discussion delivered, then it would curtail many a discussion on this forum as rarely is anyone else seeing what someone is posting about.  It's just for sharing and the gifted blessed on here I alway appreciate their experience.  Thank you all.

"How can there be a satisfactory Zs " - because there is at each accessory as each is still connected to one leg of the discontinuous CPC  ?

well i have a reasonable take away from the comments made.  thank you.   subject closed for me.

Really? Then I can see how you got your moniker Habs as I'm none the wiser!