Using cpc as neutral

[KentSparky]

is it dangerous to use the cpc in a twin / earth cable? I know it's not safe in case someone else thinks it's still an earth but is that the only reason?

 

[Pete999]

is it dangerous to use the cpc in a twin / earth cable? I know it's not safe in case someone else thinks it's still an earth but is that the only reason?

Might not be the same csa as the Phase conductor, not insulated over the entire length, what are you using as the cpc if you bodge the job by using it as the N, IT'S WRONG and against the Regulations, nothing else springs to mind other than it's Muppetry to do it.

 

[Toneyz]

Unbelievable

 

[Octopus]

Well .......... each cable should have a continuous CPC from the CU - can't remember the reg no.

 

[MJPD29]

This has to be a joke

 

[Spoon]

The OP was up at half 2 in the morning... Maybe he was 'sleep texting'??

 

[Pete999]

This has to be a joke

A bad joke at that.

 

[Wilko]

Commonly these are from a new member with a blocked profile .

 

[Spoon]

Commonly these are from a new member with a blocked profile .

MODs... Is this 'blocked profile' a glitch as the last member who had this said they hadn't changed anything?

 

[Spoon]

MODs. Carrying on from my text above:
I was curious if others also have enabled this feature. I when to the New Member Introduction section and it looks like the members who have New EF Member under their name all have this profile blocking feature enabled.
It looks like it might be a fault.

 

[Spoon]

@Dan @Lou You may want to look into my post above regarding the blocking of viewing the profile.
It looks like its a bug.

 

[Andy78]

Commonly these are from a new member with a blocked profile .

I have noticed this a lot. I was thinking it's either a setting that's set to block profile as default, or more than likely a serial winder-upperer.

 

[johnduffell]

Well .......... each cable should have a continuous CPC from the CU - can't remember the reg no.

Cpc has to be present at every termination but in fact you can get it from wherever you like.
You can even oversleeve a green and yellow insulated core with brown in a multi core cable and that still complies with the regs. But you'd only do that if you were struggling to avoid a lot of redecorating!
The bare cpc is not insulated that would be your main problem.

 

[Pete999]

Commonly these are from a new member with a blocked profile .

Why is the profile blocked? has he something to hide? very odd.

 

[johnduffell]

is it dangerous to use the cpc in a twin / earth cable? I know it's not safe in case someone else thinks it's still an earth but is that the only reason?

Same applies to any conductor that isn't identified correctly but that would show up pretty quickly in testing. The main issue is the lack of insulation and the requirement to get an earth to every termination.

 

[Wilko]

You can even oversleeve a green and yellow insulated core with brown in a multi core cable and that still complies with the regs

Hi - not to joust, but not a good idea imho and may be prohibited by 514.4.2 .

 

[johnduffell]

Hi - not to joust, but not a good idea imho and may be prohibited by 514.4.2 .

Agree it's a terrible idea when designing from scratchs but i don't agree it's dangerous and it would be picked up straight away by anyone working on the circuit.
That reg says you can't identify with green and yellow but you can insulate with green and yellow and identify by over sleeving just like identifying any other. And also you aren't allowed to use over sleeving to identify single core cables.
It's a bit like the two circuits in one accessory problem, or rings split side to side. Might confuse people but they probably are the kind of people who connect all reds and Black's in a light and wonder why the switch pops the MCB

 

[Octopus]

Cpc has to be present at every termination but in fact you can get it from wherever you like.
You can even oversleeve a green and yellow insulated core with brown in a multi core cable and that still complies with the regs. But you'd only do that if you were struggling to avoid a lot of redecorating!
The bare cpc is not insulated that would be your main problem.

So you've given me a disagree ............ hum

Reading the OP between the lines I imagine he wants to use the CPC as SL or similar .............. hence my reply.

 

[Darkwood]

MODs... Is this 'blocked profile' a glitch as the last member who had this said they hadn't changed anything?

I don't have any blocking issues as a Mod but yes it doesn't allow me to view if I log out and try view as a visitor, I assume its part of the approval system all new members are now on, it's part of the fight against spamming that we now approve all posts and activities from new members hence you haven't seen any of the spam for a while.

 

[johnduffell]

So you've given me a disagree ............ hum

Reading the OP between the lines I imagine he wants to use the CPC as SL or similar .............. hence my reply.

No offence, unfortunately i can't do any more detailed explanation at that point! But i was addressing a part of your post not your usual excellent standards!
I do think that when people are asking this kind of question, we should be precise about why it's not allowed, and appeal to both the regs and to common sense specifically where appropriate.i think a lot of things that are uncommon in domestic are actually within the regs, and sometimes the boundary between what is allowed and what isn't seems to defy common sense, but as long as we discuss properly we will help everyone to learn something new.

 

[joel89]

Not the same size as the phase conductor & a total no no

 

[Pete999]

No offence, unfortunately i can't do any more detailed explanation at that point! But i was addressing a part of your post not your usual excellent standards!
I do think that when people are asking this kind of question, we should be precise about why it's not allowed, and appeal to both the regs and to common sense specifically where appropriate.i think a lot of things that are uncommon in domestic are actually within the regs, and sometimes the boundary between what is allowed and what isn't seems to defy common sense, but as long as we discuss properly we will help everyone to learn something new.

Can't really what there is to discus John, you shouldn't use the cpc as a live conductor under any circumstances.

 

[Baddegg]

Why would you want to anyway? Just price accordingly do it properly or not at all and sleep easy......

 

[johnduffell]

Can't really what there is to discus John, you shouldn't use the cpc as a live conductor under any circumstances.

Shouldn't according to what reason though? My point is try to be specific. If this was an eicr you can't just code things because it's not common practice.
In a t&e yes as i said definitely not allowed because of the lack of insulation, however under the regs you can identify the green and yellow insulated conductor in a multi core cable as neutral or line by over sleeving.
Making sweeping statements about how you shouldn't do it isn't really helping anyone to learn something.

 

[Pete999]

In a t&e yes as i said because of the lack of insulation, however under the regs you can identify the green and yellow insulated conductor in a multi core cable as neutral or line by over sleeving.
Making sweeping statements about how you shouldn't do it isn't really helping anyone to learn something.

So what would you use as the cpc in your scenario? and can you say which Regulation says that doing what you suggest complies with BS7671.

 

[johnduffell]

So what would you use as the cpc in your scenario? and can you say which Regulation says that doing what you suggest complies with BS7671.

There's no need to have a cpc in every cable, you just need it available at every termination.
And the reg mentioned earlier covers over sleeving. You can identify any cable by over sleeving, the only restriction is you can't use green yellow identificationide anything other than cpc and you can't use over sleeving to identify a green yellow insulated single.
Don't have access to the regs right now but i can look later if necessary

 

[Octopus]

Shouldn't according to what reason though? My point is try to be specific. If this was an eicr you can't just code things because it's not common practice.
In a t&e yes as i said definitely not allowed because of the lack of insulation, however under the regs you can identify the green and yellow insulated conductor in a multi core cable as neutral or line by over sleeving.
Making sweeping statements about how you shouldn't do it isn't really helping anyone to learn something.

Best you stop digging

"is it dangerous to use the cpc in a twin / earth cable? I know it's not safe in case someone else thinks it's still an earth but is that the only reason?"

Only the OP knows what he is doing and asking and he's made no attempt to clear this up .........

 

[Octopus]

There's no need to have a cpc in every cable, you just need it available at every termination.

Best you explain that as I do disagree ............

 

[Pete999]

There's no need to have a cpc in every cable, you just need it available at every termination.
And the reg mentioned earlier covers over sleeving. You can identify any cable by over sleeving, the only restriction is you can't use green yellow identificationide anything other than cpc and you can't use over sleeving to identify a green yellow insulated single.
Don't have access to the regs right now but i can look later if necessary

Yes please would be interesting, just a point how are you going to have a cpc at every termination if you don't as you say, need a cpc in every cable, and why would you use a cable with an earth core if you didn't need it? seems very counter productive in my book, are you sure you are not misreading/misunderstanding the regulations, still if you get hold of your copy and quote the Reg number we can all have a look.

 

[Baddegg]

Got to be a wind up,if he’s considering doing it to T&E I can’t imagine he’s used many single core cables ever anyway......

 

[johnduffell]

can you say which Regulation says that doing what you suggest complies with BS7671.

514-03-02 - Every core of a cable shall be identifiable at its terminations and preferably throughout its length.
So brown sleeving at the terminations would comply, although not be preferable
411.3.1.1 - A cpc shall be run to and terminated at each point in wiring and at each accessory
So as long as one cable that has a cpc arrives at the accessory you're ok

 

[Baddegg]

Got to be a wind up,if he’s considering doing it to T&E I can’t imagine he’s used many single core cables ever anyway......

Or multi core cable Either

 

[Octopus]

514-03-02 - Every core of a cable shall be identifiable at its terminations and preferably throughout its length.
So brown sleeving at the terminations would comply, although not be preferable
411.3.1.1 - A cpc shall be run to and terminated at each point in wiring and at each accessory
So as long as one cable that has a cpc arrives at the accessory you're ok

I’ve given you a disagree on the basis that op asks about using the cpc as a live conductor - this could very easily be a single cable arriving at an accessory and therefore will not comply with the regs ....

 

[Andy78]

I think this has drifted quite far from the specific original question of using a cpc in T+E as a live conductor.

 

[johnduffell]

I’ve given you a disagree on the basis that op asks about using the cpc as a live conductor

Fair enough but i feel having stated at least 3 times that it's not acceptable in t&e due to lack of insulation and been very specific about when it isn't an is allowed and for what reason, I'm actually quite disappointed that members i respect on here are throwing around disagrees without explanation beyond that it's shouldn't be allowed.
If you read the op carefully you will note he is trying to learn and he's asking for exactly which reasons it is not allowed, i didn't take away from that that he's planning to do it. Let's try to be constructive and learn something, if the op wants to do something dangerous then that's up to him, we are here to help, right?
Hope that came across ok, I'm not trying to start a disagreement i just think i only learn something from people i disagree with (if they are also happy to discuss)
Happy Monday (just to try to relax the mood

 

[Octopus]

Fair enough but i feel having stated at least 3 times that it's not acceptable in t&e due to lack of insulation and been very specific about when it isn't an is allowed and for what reason, I'm actually quite disappointed that members i respect on here are throwing around disagrees without explanation beyond that it's shouldn't be allowed.
If you read the op carefully you will note he is trying to learn and he's asking for exactly which reasons it is not allowed, i didn't take away from that that he's planning to do it. Let's try to be constructive and learn something, if the op wants to do something dangerous then that's up to him, we are here to help, right?
Hope that came across ok, I'm not trying to start a disagreement i just think i only learn something from people i disagree with (if they are also happy to discuss)
Happy Monday (just to try to relax the mood

Posters need to learn to post better threads and answer questions

For a non spark you seem to be going out of your way to pxss people off.....

 

[johnduffell]

Posters need to learn to post better threads and answer questions

For a non spark you seem to be going out of your way to pass people off.....

Ok fair enough I'm not the thread police so maybe the op broke the rules.
Second i have no desire to annoy people, as that would be pointless. i was purely here to help everyone's knowledge including my own, if you'd rather i leave this thread just let me know and I'll unwatch this thread and let you all to it.

 

[Wilko]

There's no need to have a cpc in every cable, you just need it available at every termination.

Hi - I'm struggling to think of installing a circuit without a cpc. Some have been installed historically, but I don't think that's been since the '60s. As I've started to practice for the regs exam ( ) the two regs I could find that seem relevant are 543.6.1 and 543.2.9 .

 

[KentSparky]

Shouldn't according to what reason though? My point is try to be specific. If this was an eicr you can't just code things because it's not common practice.
In a t&e yes as i said definitely not allowed because of the lack of insulation, however under the regs you can identify the green and yellow insulated conductor in a multi core cable as neutral or line by over sleeving.
Making sweeping statements about how you shouldn't do it isn't really helping anyone to learn something.

Well said

 

[johnduffell]

I'm struggling to think of installing a circuit without a cpc

Thanks for the regs help! I can't think of a circuit without a cpc either, that would certainly not comply and i have not suggested it.

the two regs I could find that seem relevant are 543.6.1 and 543.2.9

"Where overcurrent protective devices are used for fault protection, the protective conductor shall be be incorporated into the same wiring system as the live conductors or in their immediate proximity."
Same wiring system, but not necessarily the same cable, as i understand it.
The latter reg is talking about the special case of rings which are not under discussion but it states that the cpc should also be a ring.

 

[Andy78]

Thanks for the regs help! I can't think of a circuit without a cpc either, that would certainly not comply and i have not suggested it.


"Where overcurrent protective devices are used for fault protection, the protective conductor shall be be incorporated into the same wiring system as the live conductors or in their immediate proximity."
Same wiring system, but not necessarily the same cable, as i understand it.
The latter reg is talking about the special case of rings which are not under discussion but it states that the cpc should also be a ring.

Same wiring system does not necesarilly mean the same cable, but can do, and in the case of the question posed here, a multicore cable was mentioned, which is the wiring system in this case.

Rings are not under discussion, but they might be as the OP gave sparse information. You did bring up quite a few points yourself which were not under discussion.

 

[Richard Burns]

The most relevant regulation for providing a cpc to a circuit that is protected by ADS is probably 411.3.1.1 fourth paragraph: a circuit protective conductor shall be run to and terminated at each point in wiring and at each accessory except a lampholder having no exposed conductive parts and suspended from such a point.

 

[johnduffell]

Same wiring system does not necesarilly mean the same cable,

Agree, that's basically what i meant when i was saying each cable didn't have to have a cpc as long as there was one available at every termination.

You did bring up quite a few points yourself which were not under discussion.

Sorry, i didn't mean to, as far as i can see from rereading my posts every single one was either addressing the question the op originally posted or attempting to clarify information provided by others, together with informative examples for further clarification.

 

[Rpa07]

‘Or Immediate proximity’ I read as 6491 singles in conduit or trunking taking the same complete route as both or all lives. This is in order to terminate at each accessory.

Thanks for the regs help! I can't think of a circuit without a cpc either, that would certainly not comply and i have not suggested it.


"Where overcurrent protective devices are used for fault protection, the protective conductor shall be be incorporated into the same wiring system as the live conductors or in their immediate proximity."
Same wiring system, but not necessarily the same cable, as i understand it.
The latter reg is talking about the special case of rings which are not under discussion but it states that the cpc should also be a ring.

 

[Adam W]

No offence, unfortunately i can't do any more detailed explanation at that point! But i was addressing a part of your post not your usual excellent standards!
I do think that when people are asking this kind of question, we should be precise about why it's not allowed, and appeal to both the regs and to common sense specifically where appropriate.i think a lot of things that are uncommon in domestic are actually within the regs, and sometimes the boundary between what is allowed and what isn't seems to defy common sense, but as long as we discuss properly we will help everyone to learn something new.

There are reasons we work to a standard, primarily for safety.
I don't believe it is helpful for anyone, especially someone who has just begun learning about the subject to routinely challenge the way everything is done seemingly in an attempt to push boundaries and think outside the box.

Unconventional installation methods, or as I call it "doing it weird" is a tell-tale sign of someone who doesn't know what they're doing; the more I've learned about electrics the more I've been able to appreciate that a lot of consideration and knowledge goes into the writing of BS7671 and that deviating from the standard should only be done in exceptional circumstances and not as a norm "because you can".

In this instance the CPC in a T&E is not suitable to use as a neutral because it is not the same size as the other (line) conductors and could overheat, the outer sheath of a T&E is intended for mechanical protection and not electrical insulation; sleeving is intended for identification and not electrical insulation - it is not fixed to the conductor so can easily slide off to reveal a live part where the outer sheath is stripped back or could fall off altogether.

This is basic stuff.

As a minimum it should be enough to say that we don't do it, at a push that regs forbid it, and leave it as that.

 

[johnduffell]

‘Or Immediate proximity’ I read as 6491 singles in conduit or trunking taking the same complete route as both or all lives. This is in order to terminate at each accessory.

Interesting didn't think about that re wiring systems:, so if two 3 core flexes routed together you could do it in one of them but not if they went via different routes? Or is that only if they are in the same containment rather than being sheathed?
That's more strict then i was originally thinking.

 

[Rpa07]

@johnduffell you call it strict - I call it safe, as all installations should be.
We all need to sleep at night and installing safely to regulations, that are set in place for a reason, make my pillow feel like a cloud!

 

[johnduffell]

.

@johnduffell you call it strict - I call it safe, as all installations should be.
We all need to sleep at night and installing safely to regulations, that are set in place for a reason, make my pillow feel like a cloud!

I meant strict in the mathematical sense of more tightly defined, not in the sense that i disagreed with it.
Anyway thanks for helping!

 

[Colin33]

Hi - I'm struggling to think of installing a circuit without a cpc. Some have been installed historically, but I don't think that's been since the '60s. As I've started to practice for the regs exam ( ) the two regs I could find that seem relevant are 543.6.1 and 543.2.9 .

Not so long ago I was wiring up an underfloor heating system. The controls for the heating were all downstairs, along with domestic hot water controls. The zone valves, along with the water tank and gas boiler were all in the loft. To complicate things, there was also a solar thermal input and a 'warm loop' system. I had a twin n earth cable feeding the system and supplying a large junction box with its cpc. I also had two 5 core flex going up to the JB in the loft. Therefore, I had two green/yellow cores which were not required as a cpc. I did need to use one of these as a live conductor and oversleeved it at each end accordingly. Isn't this an example of when an unused cpc is legitimately used as a live conductor?

 

[davesparks]

Not so long ago I was wiring up an underfloor heating system. The controls for the heating were all downstairs, along with domestic hot water controls. The zone valves, along with the water tank and gas boiler were all in the loft. To complicate things, there was also a solar thermal input and a 'warm loop' system. I had a twin n earth cable feeding the system and supplying a large junction box with its cpc. I also had two 5 core flex going up to the JB in the loft. Therefore, I had two green/yellow cores which were not required as a cpc. I did need to use one of these as a live conductor and oversleeved it at each end accordingly. Isn't this an example of when an unused cpc is legitimately used as a live conductor?

No, that’s an example of very poor workmanship, the correct cables should have been installed for the job.

Where were the 5 core cables coming from? Did that point not need a cpc?