Best way to check continuity of cpc for lighting

[Tbob27]

20 y old lighting circuit with cpc at the board but terminating into class 2 recessed down light fittings. Looks like there is a junction box in the ceiling void feeding the light with L&N but I can't access the junction box so not sure how can prove continuity of the circuit?

 

[westward10]

Unless you can physically access the cpc then you cannot.

 

[Tbob27]

Unless you can physically access the cpc then you cannot.

That's what I was expecting, how then is the circuit treated on schedule of tests, just enter a Zs for wherever you can measure on the circuit even if it's not necessarily the furthest point?

 

[James]

in reality. if they are all class 2 lights, the obvious danger points are the switches if they are conductive.

i would start by checking there.

 

[Tbob27]

in reality. if they are all class 2 lights, the obvious danger points are the switches if they are conductive.

i would start by checking there.

Switches are all plastic with no cpc

 

[westward10]

Are you doing an EICR.

 

[Tbob27]

Are you doing an EICR.

Customer wants a CU change to put in a new shower circuit (currently no ways left or RCD protection) but doesn't want an EICR so trying to check continuity of all cpcs before IR test, done Zs at all sockets to make sure there aren't any underlying concerns

 

[littlespark]

Can you put in a “shower” or “garage” board with rcd dedicated just for the new shower and not touch the existing circuits as they are?

changing the board involves as much testing as an EICR anyway

 

[Tbob27]

Can you put in a “shower” or “garage” board with rcd dedicated just for the new shower and not touch the existing circuits as they are?

changing the board involves as much testing as an EICR anyway

There's no room for another board unfortunately

 

[timhoward]

I’ve been known to try a B6 rcbo connected to a plug top, plugged into the sockets circuit, and wago the lighting circuit to it as a quick sanity check that nothing will cause instant tripping. Not desperately safe of course but proves the point.
Sometimes you can het a clamp meter around L and N which is a safer test.

Apart from that I’d crack on - do the other circuit and then IR tests (L+N to cpc bar)

(I think BPG1 covers this situation of a cu change with no cpc on lighting btw.)

 

[Tbob27]

I’ve been known to try a B6 rcbo connected to a plug top, plugged into the sockets circuit, and wago the lighting circuit to it as a quick sanity check that nothing will cause instant tripping. Not desperately safe of course but proves the point.
Sometimes you can het a clamp meter around L and N which is a safer test.

Apart from that I’d crack on - do the other circuit and then IR tests (L+N to cpc bar)

(I think BPG1 covers this situation of a cu change with no cpc on lighting btw.)

Thanks, there is a cpc at the CU just cannot find where it terminates at a particular class 2 lamp on the circuit as Junction box feeding it is inaccessible so guess i will just have to rely on where I can check it elsewhere on the circuit

 

[timhoward]

I wouldn’t waste too long on it - my main concern would be whether it will cause me grief once reconnected.
Regarding the paperwork you can’t get an R2 or Zs so you’ll have to add a note to that effect, and you are adding RCD protection which will serve as last resort fault protection in absence of verifiable fault protection via CPC.
(Obviously I’d be recommending lighting is rewire in due course too.)

 

[Tbob27]

I wouldn’t waste too long on it - my main concern would be whether it will cause me grief once reconnected.
Regarding the paperwork you can’t get an R2 or Zs so you’ll have to add a note to that effect, and you are adding RCD protection which will serve as last resort fault protection in absence of verifiable fault protection via CPC.
(Obviously I’d be recommending lighting is rewire in due course too.)

Thanks for your comments- makes sense