No CPC on lighting circuit ............

[Octopus]

OK, lets have a decent discussion about this as I'm sure there will be a number of opinions!

Have done an EICR on a 40 + year old flat. The lighting circuit is wired in singles and utilises the steel conduit as the CPC. Out of the 6 lights and using my R2 wander lead, only 2 have an acceptable reading - the remaining 4 have 200 ohms

The CU is a dual RCD and there are no metal fittings or switches

So do I:

A: Suggest a "no CPC" label be added and give a "satisfactory" ?

or

B: tell the owner the lighting circuit needs a rewire and give it an "unsatisfactory"?


Thanks

Tin hat on!

 

[telectrix]

being a bit of a "old installation " geek, i'd maybe have a go at repairing the conduit cpc, if it weren't a massive job. failing that, your option A, with a recommend that the circuit/s would benefit fron either a rewire, or the addition of a cpc conductor.

 

[westward10]

It has a cpcs, the conduit. Lack of an earth either means the light fittings are incorrectly connected or continuity of the conduit has broken down.

 

[westward10]

It is never satisfactory if continuity of the conduit is breaking down. You cannot fit a notice stating no cpc because there is.

 

[Octopus]

It is never satisfactory if continuity of the conduit is breaking down. You cannot fit a notice stating no cpc because there is.

But as I've proved without doubt that 4 of the positions don't have earth continuity, then what would you do?

 

[telectrix]

problem being that the conduit itself may not be earthed. it's all weel and good to use classII fittings on a light circuit with no cpc. but here you have metal conduit not earthed.

 

[The Ghost]

I suppose the conduit is the type where it is buried in the ceiling? It sounds like effectively the lighting is without a cpc and from a risk perspective I would treat it as that. The likliehood of repairing it is quite low. In which case what were your Mohm readings, presumbly good as the circuit has RCD protection. Any Class 1 fittings?

 

[westward10]

But as I've proved without doubt that 4 of the positions don't have earth continuity, then what would you do?

I would C2 it obviously unsatisfactory. As for correcting it, yes you could run a separate cpc if that is possible but that would be no guarantee all the conduit is effectively earthed. With such a wiring system I would probably date it 55+ years and suggest it should be rewired.

 

[Octopus]

I suppose the conduit is the type where it is buried in the ceiling? It sounds like effectively the lighting is without a cpc and from a risk perspective I would treat it as that. The likelyhood of repairing it is quite low. In which case what were your Mohm readings, presumbly good as the circuit has RCD protection. Any Class 1 fittings?

Conduit in ceiling
RCD protection
no class 1 fittings

 

[davesparks]

Steel conduits containing singles and not properly connected to earth is a C2 in my opinion.

 

[Octopus]

And IR test between LN and conduit?

At the accessible points OK !

 

[telectrix]

write it up as a C2 and then advise client of the options.

 

[buzzlightyear]

that would be c2. rewire of the lighting.

 

[The Ghost]

OK!

 

[telectrix]

or quote £4000 to install gas lighting.

 

[buzzlightyear]

who going to fit that tele, fanny by gas light

 

[KEV 1 N]

I come across this a lot testing some of the old university buildings, I class it as c2, as the conduit could become live under a fault and the protective device will not operate.
We have to rectify it either by pulling in new cpc from the DB to each point or connect a cpc from the last point where the earth reading is acceptable and then work back to the last point on the circuit, some times easier said than done!

 

[7029 dave]

IMO, singles in conduit= full conduit system, broken earth continuity in parts, c2 this is the very reason why I always pulled in a separate cpc in, on all my circuits in a full conduit system.!

 

[KEV 1 N]

They never used a cpc in the old days, just relied on the metal containment. Although having said that, I tested another university building built in 1991 and its all metal containment with no seperate Earth, done properly though, earth couplers, serrated washers used throughout, all good readings!

 

[7029 dave]

They never used a cpc in the old days, just relied on the metal containment. Although having said that, I tested another university building built in 1991 and its all metal containment with no seperate Earth, done properly though, earth couplers, serrated washers used throughout, all good readings!

I know, but rusty conduit concealed in walls etc after many years it fails. All council rewires I have done in the past have pulled in a cpc on existing conduit without cpc, and when you can't its all surface work.