cpc in pvc conduit?

[Cazmac1]

Hi all, I was testing an installation today and every thing seems to be in order till I found a piece of white pvc conduit with a single 2.5 brown cable in it with no cpc. The conduit had been installed to pick up a permanent feed to a PIR from an emergency light fitting.
Both lights and the PIR were all earth correctly Just not through this conduit link. Now my question is, is this allowed? If I was running the cable I would put a cpc in there as as it forms part of the circuit it should have a cpc. Is there a reg relating to running a cable this way. Of course if the conduit got damaged there would be no earth path via the conduit, so the cpc may pick up the fault but there is no guarantee that the cpc and the live conductor would be damaged at the same time???

 

[Brightspark2]

But that's not why we run a cpc in?...we run a cpc in to earth the exposed conductive parts of Installation...

 

[Cazmac1]

not sure if what you have stated is correct? circuit protective conductor, protects the circuit, not the same as bonding or earthing?

 

[Cazmac1]

looks like I'll be getting the big book out

 

[Silly Sausage]

There is reg stating that a cpc has to be run to every point on a circuit.

 

[Guest77]

Hi all, I was testing an installation today and every thing seems to be in order till I found a piece of white pvc conduit with a single 2.5 brown cable in it with no cpc. The conduit had been installed to pick up a permanent feed to a PIR from an emergency light fitting.
Both lights and the PIR were all earth correctly Just not through this conduit link. Now my question is, is this allowed? If I was running the cable I would put a cpc in there as as it forms part of the circuit it should have a cpc. Is there a reg relating to running a cable this way. Of course if the conduit got damaged there would be no earth path via the conduit, so the cpc may pick up the fault but there is no guarantee that the cpc and the live conductor would be damaged at the same time???

I would say definately no, having a live phase conductor in a pipe without an earth with it not right, if a metal pipe which was earthed then not so bad, however I don't like the fact a single core run alone anyhow, I have no BGB with me but there is no doubt a reg will exist somewhere regarding an earth at all points and conductors running alone in non earthed containment, someone with a regs may help out, but your concern is valid IMHO.

 

[Brightspark2]

not sure if what you have stated is correct? circuit protective conductor, protects the circuit, not the same as bonding or earthing?

Bonding is connecting extraneous conductive parts to earth...

Defination if a cpc taken from BS7671: A protective conductor connecting exposed conductive parts of equipment to the main earthing terminal.

This is the same defination as earthing so yes earthing and cpc are the same.

Don't let the name confuse you squire, it isn't there to provide an earth path if the cable is cut or even protect the circuits length at all.

 

[richy3333]

Won't the conductor get lonely without a neutral and CPC

 

[Marvo]

Won't the conductor get lonely without a neutral and CPC

Apart from loneliness I wouldn't see a good electrical reason that it wouldn't be acceptable as described in this particular scenario. Is there actually a reg in the 7671 that prohibits it?

 

[Cazmac1]

thanks for the answers. Going to fail that circuit

there are a few regs in section 543.5 onwards that seem to say that there needs to be a cpc

 

[davesparks]

What sort of test are you carrying out? IV or EICR?

The nearest thing to it is reg 543.6.1 but that doesn't require the cpc to be run adjacent to every conductor of the circuit so I don't think you can actually justify 'failing' this

 

[Cazmac1]

What sort of test are you carrying out? IV or EICR?

The nearest thing to it is reg 543.6.1 but that doesn't require the cpc to be run adjacent to every conductor of the circuit so I don't think you can actually justify 'failing' this

(EICR)
It more than meets the requirements of basic protection but I not sure if it would meets the requirements for ADS?
It's a tricky one and as we all know the regs can be full of contradictions.

 

[Guest77]

Well it is a tough call, in the old days a double insulated single core was the norm in houses run between switches etc, regs change all the time though and I cannot actually quote a reg (if there is one) to suggest a fail on the EICR, bad practice I would suggest but again no reg no fail, we need someone with a regs book to look closely at section 4.

 

[Risteard]

A length of conduit is not a point. You have already stated that there is a cpc at all points in the wiring, so what is the problem?

 

[Guest77]

Well you could argue if the conduit was damaged the phase conductor inside could become damaged and a potential electric shock for someone, the supply would not switch off if no other core run alonside it, thats one argument.

 

[davesparks]

It is also possible, and not all that uncommon to damage a bit of flex or T&E and only expose the copper of the live conductor.

 

[Risteard]

Well you could argue if the conduit was damaged the phase conductor inside could become damaged and a potential electric shock for someone, the supply would not switch off if no other core run alonside it, thats one argument.

That doesn't mean that there is a requirement, however. In fact even with a cpc run alongside the phase conductor there is absolutely no certainty that the phase wouldn't be damaged without creating an earth fault.

 

[davesparks]

If it is an EICR then it cannot 'fail' it can merely be found unsatisfactory and a suitable code given.

Is it immediately dangerous?
Is it potentially dangerous?
Does it require improvement?

 

[Guest77]

It is also possible, and not all that uncommon to damage a bit of flex or T&E and only expose the copper of the live conductor.

very true, still think running one live core in a plastic pipe is carp, but thinking it isn't the same as it being against the regs.

 

[Risteard]

If it is an EICR then it cannot 'fail' it can merely be found unsatisfactory and a suitable code given.

Is it immediately dangerous?
Is it potentially dangerous?
Does it require improvement?

I can't see any breach of the Wiring Regulations unless it was to enter a ferrous enclosure on its own at some point.