bearing in mind not a full test done as yet to see what accessories may be connected to each other:

A small lighting circuit (~9 switches and lighting points) but across 4 floors in a student house, wired in t&e, has no continuity at lighting points or switches back to the met (though CPC is present at the accessories). Probably a few junction boxes somewhere will exist too.

I am interested in your opinions on moving to the 'all class 2 fix', using nylon screws, rcbo, notices on DB etc please if not feasible (for whatever) to reestablish the cpc/earth.

Most of the accessories are already plastic (only 2 metal lighting units to change); the back boxes are metal of course (some have nylon lugs).

My opinion is that this does not rectify the issue where the circuit was originally wired to have a CPC and subsequent work has rendered it ineffective. Without an RCBO addition, a fault to earth may create a voltage on the CPC across parts maybe connected together and whilst it may be accessories are insulated to touch, it seems to me to be an cop-out remedy, but is there regulation to say it cant be done.

If it were originally designed without a CPC, I may think differently to the idea.

I do see posts on here and elsewhere where class 2 is chosen as a fix, but in this case what's the general view on it?

Thanks for your comments (if any).
Chris

Sounds like one or two places I've visited. (One had all the c.p.c.s disconnected at the light fittings and neat little squares of cellotape over the switch screws - and the c.p.c. was still live )

I think you'd stumble on 412.1.3/412.2.3.2 which requires a c.p.c. to every point, unless the installation is under effective supervision. (I've seen what students, especially student engineers, can do to student accommodation).

I've a feeling there used to be an objection to relying on non-conductive screws for class-2 insulation too (something about a loose screw being replaced with a metal one, not realising the reason for a plastic one being there in the first place, but I think that's not BS 7671). There still remains the problem of "live wall" with steel back boxes.

- Andy.

I think there is a world of difference between a circuit without a CPC and a circuit with floating CPCs.
Floating CPCs present a potential danger to whatever and wherever they run.

id try to establish to what points from the CU they are earthed, and how the remainder can be interconnected. Can a tiny bit of slack not be puled down to achieve a connection?

IMHO the 'all class 2' option is a work around on a old, old installation where the owners simply will not pay to have it rewired, or cannot have the disruption (elderly foe example), not an excuse for a landlord to have a sub standard installation.

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Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry