Using CPC as live conductor.... ok i know, but...

[uksparks]

Hi,

Had to change a bathroom fan at the weekend for someone and they wanted it to be on a timer, but couldnt as the cable was buried in the wall and wouldn't move etc..

the cable that fed it was a three core flex, I the earth was not being used anyway due to the load on the end etc.

I know you are not meant to use the CPC as a live conductor, but if its flex and the same CSA and you were to correctly identify it with brown etc, would it have then been acceptable?

I didn't do it, but it made me think, oh i so could have used it, but it just seemed wrong. I can understand why you wouldn't do it in twin and earth, but surely where its flex or all conductors are the same CSA and have their own sheathing on them inside the outer, would it have been acceptable or not?

I am going to say not on the basis CPC is CPC and nothing else, any thoughts would been welcomed.

 

[telectrix]

I remember a story going round a while back (90s) about a plumber who cut into an existing boiler wiring flex that had cpc as live - can't remember details but he connected the cpc to earth term somewhere in his jb and result was fatal shock for homeowner off the kitchen sink.

i can only see that happening if there was no earthing on the installation.

 

[Hawkmoon]

Bear in mind he would have used this 'earth' terminal to earth whatever he was installing (new boiler/whatever) making it live and anything metallically connected to it (eg copper pipes to sink)

As I say I don't remember details but there could have been other factors contributing.

 

[telectrix]

then if the installation was earthed, the OCPD would have operated as soon as he'd connected it to a line conductor.

 

[Plonker 3]

yep fair enough, i cant find the article link but found this on a forum page......

View attachment 23390

I have no idea who wrote that, but the reg they quoted applies to PEN conductors. So even the diagram used is a load of baloney.

 

[Pete999]

yep fair enough, i cant find the article link but found this on a forum page......

View attachment 23390

Might be barking up the wrong tree but doesn't the Class two logo mean anything to anyone, just saying

 

[Hawkmoon]

Tel...
The way I understood it the plumber thought that the cpc in the flex was his earthing source so everything he did from that point on was isolated from the actual earth (no real cpc present in his jointing box) - no reason for OCPD to operate

 

[itselectric]

I remember a story going round a while back (90s) about a plumber who cut into an existing boiler wiring flex that had cpc as live - can't remember details but he connected the cpc to earth term somewhere in his jb and result was fatal shock for homeowner off the kitchen sink.

It was in the papers in the nineties as you say. the plumber got time for it.

 

[eddielarge]

Omg Dillb is your glass half full such a negative response to a sensible question

 

[wayneob]

used to come across this when doing boiler upgrade work on the s-plan and y-plan systems, the way I see it is that the CPC is there to protect the cable aswell, bad practice.

 

[itselectric]

It was in the papers in the nineties as you say. the plumber got time for it.

I 've had another think on this and I'm almost certain it was an electrician, not a plumber, who was at fault.
When he was questioned in court he couldn't even say where the consumer unit was

 

[Badged01]

I 've had another think on this and I'm almost certain it was an electrician, not a plumber, who was at fault.
When he was questioned in court he couldn't even say where the consumer unit was

Probably been a Electrical Trainee "electrician" who did it then ............. hang-on, did they do Electrical Trainee courses in the 90's?

 

[Hawkmoon]

I 've had another think on this and I'm almost certain it was an electrician, not a plumber, who was at fault.
When he was questioned in court he couldn't even say where the consumer unit was

I think for the sake of forum harmony we should stick to blaming a plumber lol

 

[Brightspark2]

Reg 514.4.2 says no you cant do that.

It doesn't. If it's over sleeved at the end than its ok.

Unless it's a single core cable which can not be sleeved over.


But as darkwood says it's not good practice...

 

[iamelectric]

i would have had no problem using that flex , brown sleeving on both ends whats the problem , common sense over rules the the regs sometimes , tin hat firmly on

 

[DPG]

I have no idea who wrote that, but the reg they quoted applies to PEN conductors. So even the diagram used is a load of baloney.

Must a typo - I think they mean 514.4.2. Daz

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The diagram doesn't show a PEN conductor.