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.

 

[telectrix]

whether there's a cpc or not, damage could result in exposed live parts without ADS occuring, so what is the point of a cpc running alongside the L conductor? a an;t see any reg, breached whatewver.note in the comments sesction is all i'd put, just to show that i'd spotted it. c

 

[Cazmac1]

this was my initial point of view. I suppose you could argue that you are increasing the protection even though it may not actually work in practice. I have read through section 4 quickly but I just to tired to take it in. have a read when a bit fresher.

 

[Risteard]

If you believe that it is likely to suffer damage then perhaps pvc conduit is not the correct containment rather than wanting a cpc which is not required and would not afford any protection.

 

[davesparks]

If it doesn't work in practice then you aren't achieving anything.

If you are going to put this down as an observation requiring any action on an EICR then you need to be able to justify it in the regulations. There is no regulation requiring a cpc to be run alongside every conductor, only one that requires the cpc to be contained within the same wiring system.

 

[Cazmac1]

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

It does enter the light fitting which is ferrous but as I said earlier all other points are earthed, so a short there would result in the protective device tripping.

 

[davesparks]

Then you have an eddy current issue

 

[Marvo]

Only if it entered the fitting through a different hole to the CPC and neutral.

I combed through my local SA regs just out of interest and there's also nothing that specifically forbids a single live insulated conductor in its own conduit unless you can class conduit as a sheath as well as containment.

 

[Deleted member 26818]

It's a requirement of the Regulations that all conductors (including the CPC) of a circuit a within the same ferrous magnetic containment (if used).
As this conductor is not within a ferrous magnetic containment it is not required to be within the same containment as any other circuit conductor.
No it does not require another CPC to be run with it either.

 

[davesparks]

It's a requirement of the Regulations that all conductors (including the CPC) of a circuit a within the same ferrous magnetic containment (if used)..

Which regulation is that?

 

[Deleted member 26818]

I'm in a Cafe.
I don't carry copies of the Regs around with me.
If I recall correctly, it's 521.5.2.

 

[Marvo]

I'm in a Cafe....

Hmmm, sounds like a place that might not have a liquor license. I suggest you might want to relocate pronto .

 

[Deleted member 26818]

Not sure if this is the exact wording:

Single-core cables armoured with steel wire or steel tape shall not be used for an a.c. circuit. The conductors of an a.c. circuit installed in a ferromagnetic enclosure shall be arranged so that all line conductors and the neutral conductor, if any, and the appropriate protective conductor are contained in the same enclosure.

Where such conductors enter a ferrous enclosure, they shall be arranged such that the conductors are only collectively surrounded by ferrous material.

It's not actually a Cafe, it's an Ice Cream Parlour.

 

[Guest55]

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

but not to accompany every cable installed.......

 

[Guest55]

Going to fail that circuit

then you'd be making a mistake.......

 

[Cazmac1]

then you'd be making a mistake.......

Yes it would be, I've now changed my mind as it seems there is nothing that forbids this type of arrangement.
Thanks for all the replies.