Solution to a C2 - No CPC on lighting circuit

[Aaron b]

I checked for any voltage on the bare earth and there wasn't any and you couldn't feel anything when you touched it but every time it made contact with the metal DB there were small visible sparks. I put this down to ghost voltage and carried on but it is worth thinking about.

I've had it with leakage current, with 120V ish floating and only 0,08mA there was still quite a spark.

But this isn't a circuit with[out a] CPC, this is a circuit which has a CPC with no continuity to the MET.

True. I see that quite a bit with downlights not being terminated correctly and it's definitely a good point.

I've been caught out before where the lights weren't earthed and no labels on the CU. With DIY and people not testing it could easily go unnoticed.

 

[westward10]

I've had it with leakage current, with 120V ish floating and only 0,08mA there was still quite a spark.

True. I see that quite a bit with downlights not being terminated correctly and it's definitely a good point.

I've been caught out before where the lights weren't earthed and no labels on the CU. With DIY and people not testing it could easily go unnoticed.

You have to remember these notices are not prescribed by BS7671, in my opinion a poor solution to a situation which should be given urgent attention.

 

[7029 dave]

I have a situation my gf mother's house was built in the late 50,s, although pvc cables the lighting circuit has no CPC, a few class 1 fittings have been put up, have said needs rewiring but the old girl is 90 years old not interested have had to do some mantaince like for like as such all I can do is replace with class ll fittings. Rewiring is the only solution.

 

[timhoward]

It's always an interesting topic.
If no CPC at all, in the past I have run a 4mm CPC to every point and replaced the switch drops. I probably wouldn't do that any more as since the advent of Quinetic gear it's a better solution to stick some quinetic gear in the airing cupboard and run new feeds to the lights. Sometimes there's an old immersion circuit ready and waiting to power it.

A CPC with no continuity (as already stated) is a different kettle of fish. While you could work out where the breaks are and add 4mm CPC to the relevant points so all the points are earthed again, the reason for the lack of continuity hasn't been found and that doesn't sit right with me as there could be a dangerous reason behind it.
So at a minimum it would have to be a new cable from the board to as many points as required for there to be a continuous CPC again.
If it's a 'junction box' lighting install this becomes a right pain very quickly!

 

[pc1966]

A CPC with no continuity (as already stated) is a different kettle of fish. While you could work out where the breaks are and add 4mm CPC to the relevant points so all the points are earthed again, the reason for the lack of continuity hasn't been found and that doesn't sit right with me as there could be a dangerous reason behind it.

The issue is the time to identify the CPC fault versus simply biting the bullet and rewiring.

You might be able to use a wander lead around the switches and lamps and establish that most CPCs are linked, and just the CPC to some junction missing so one run of 4mm might fix the lot, but that would be a very optimistic outcome!

 

[ipf]

The issue is the time to identify the CPC fault versus simply biting the bullet and rewiring.

You might be able to use a wander lead around the switches and lamps and establish that most CPCs are linked, and just the CPC to some junction missing so one run of 4mm might fix the lot, but that would be a very optimistic outcome!

...and that it could soon end up costing more than a circuit rewire, a bit of a gamble and you're still left with the old wiring.