NICEIC Certification Scheme NICEIC’s Connection magazine (using CPC as a live conductor)?

[BigSi]

I was reading the latest issue of the NICEIC’s Connection magazine, when came across an article about wiring extractor fans. I didn’t read it in depth (was in the library at the time!!!), but from what I can gather you can now use the cpc in a flex (flex only, not hard wired) as a live conductor from the connection point to the fan.


It refers to changing a fan for a unit with a timer, and the now sleeved cpc can be used as a live cable (presumably the switched feed)? But I couldn’t quite figure out how this would be of benefit as it’s still connected to the connection point which when I looked last only had one live in, one live out.


Or have I totally missed the point altogether? :stupid:

 

[chilliwilly]

I think you have.

Its refering that you can use the green and yellow core wthin a flex as a live/neutral conductor, as long as you flag it thus at both ends. But certainly not a cpc within a twin and earth cable, as it would only be single insulated and carrying a voltage over 50 volts and not satisfying basic protection.

As most fans are class II/double insulated/reinforced insulated, they don't require to be connected to earth, and as most modern fans incoroporate a run on timer. It will save having to rewire them with 4 core to replace the 3 core.

There are still electricians that think you can't use a green and yellow core within a flex as a live/neutral conductor? And they are just veryifyng, its not a departure if used as one.

 

[stuartcourt]

also I get the fan rarely has an earth but surely the cable still needs an earth

 

[gazzamikes]

I agree with bigsi I read it as even though sheeved with brown it can't be done, no explanation as to why in there though just a couple of pics showing

 

[telectrix]

well, i wouldn't do it. 514.4.2. for one.

 

[chilliwilly]

How would you go on with a multicore all the same colour?

 

[telectrix]

guess?

 

[Amp David]

also I get the fan rarely has an earth but surely the cable still needs an earth

For what reason?

 

[stuartcourt]

for instance incase someone puts a nail through it

 

[Guest55]

for instance incase someone puts a nail through it

and what guarantee is there than the nail hit will operate the circuit device ?
absolutely none.
you can hit the live and nothing else with a twin & earth cable and nothing will trip.
there is no requirement for a cable to contain a cpc just for the sake of protecting the cable.
that is only achieved with swa & pyro , hence the relaxation of rcd protection.
;-)

 

[Amp David]

And the CPC is there for that reason is it?

 

[stuartcourt]

amp david I did not think it there for that reason but did think it part of the reason (Biff now know after 20 years my mistake ha ha) so I could run 2 core cable and a separate earth if I felt so inclined

 

[Guest55]

yes.
its one of the ways available of improving cpc free lighting circuits in millions of homes within the uk.
;-)

 

[Amp David]

It made me chuckle when i was told I couldn't run a single insulated and sheathed cable as it didn't contain a CPC.

 

[Amp David]

amp david I did not think it there for that reason but did think it part of the reason (Biff now know after 20 years my mistake ha ha) so I could run 2 core cable and a separate earth if I felt so inclined

You could, but would be a nice 4mm if not in any containment.

 

[stuartcourt]

I have even always ran a four core to double insulated tank stats to take a cpc along, what a nob cant believe it, but no more 3 core all the way off out now to have a long hard think

 

[Amp David]

Good practice though stu, at least there's a CPC there if it ever gets swapped for one that requires the CPC

 

[Guest55]

work smart and keep that cash firmly in pocket.
:-D

 

[chopper76]

NICEIC’s Connection magazine (using CPC as a live conductor)?

The cable may not contain a cpc in this way of wiring said extractor fan, and as previously stated there isn't a requirement just to protect the cable but if you are concerned about damage it does carry a neutral within it anywhoo

 

[vaughant]

Seen it done in industry a few times but generally as a bodge!!!!

 

[Tim]

well, i wouldn't do it. 514.4.2. for one.

From 514.4.2:
"Single-core cables that are coloured green-and-yellow throughout their length shall only be used as a protective conductor and shall not be over-marked at their terminations, except as permitted by Regulation 514.4.3 [PEN conductors]"

That reg only covers single core condutors as far as im aware (correct me if im wrong) so a flex G/Y suitably sleeved should be ok.

I found this on a eicr recently and didnt code it as it was correctly sleeved, posed no danger and did not break any regs by my interpretation.

Ill happily be corrected if im wrong.

Tim

 

[GLENNSPARK]

I think you have.

Its refering that you can use the green and yellow core wthin a flex as a live/neutral conductor, as long as you flag it thus at both ends. But certainly not a cpc within a twin and earth cable, as it would only be single insulated and carrying a voltage over 50 volts and not satisfying basic protection.

As most fans are class II/double insulated/reinforced insulated, they don't require to be connected to earth, and as most modern fans incoroporate a run on timer. It will save having to rewire them with 4 core to replace the 3 core.

There are still electricians that think you can't use a green and yellow core within a flex as a live/neutral conductor? And they are just veryifyng, its not a departure if used as one.

no it bloody wouldn`t...
there would be no insulation on this at all....sheething is not classed as insulation
so, explain please why the CPC is not insulated in flat cable...

 

[somersetsparks]

It has always been Acceptable to use the G/Y core of a flex sleeved as a live conductor as far as I'm aware,
Another case of you wouldn't do it if you had to install the cable, but you would definately do it to save smashing up a bathroom

 

[telectrix]

From 514.4.2:
"Single-core cables that are coloured green-and-yellow throughout their length shall only be used as a protective conductor and shall not be over-marked at their terminations, except as permitted by Regulation 514.4.3 [PEN conductors]"

That reg only covers single core condutors as far as im aware (correct me if im wrong) so a flex G/Y suitably sleeved should be ok.

I found this on a eicr recently and didnt code it as it was correctly sleeved, posed no danger and did not break any regs by my interpretation.

Ill happily be corrected if im wrong.

Tim

you quoted para.2 of the reg. i was referring to para.1. no mention of single core in there.

 

[Richard Burns]

If you have used a three core flex and sleeved the green and yellow to use as a live conductor, then unless you also run a separate cpc then you would no longer be complying with 411.3.1.1 that requires a cpc at every accessory and joint (bar a lampholder).

I would, unfortunately, agree that it is possible to use a green and yellow insulated core of a multicore cable for a live conductor if suitably sleeved, but I would definitely not like it; based on the section Tel identifies that says green and yellow is a protective conductor only; admittedly the sleeving "makes it" non green and yellow but still would not like to do it.

 

[chilliwilly]

no it bloody wouldn`t...
there would be no insulation on this at all....sheething is not classed as insulation
so, explain please why the CPC is not insulated in flat cable...

Insulation is used as a method of basic protection, a bare cpc is insulated in a sheathed cable due to the nature of its design and manufacture, and remains insulated until terminated or damaged, if it wasn't it would be exposed and causing further exposure to the inner single insulated cores. You would also be able to measure a potential difference between a live conductor and the cpc within a sheathed cable if it wasn't insulated?

The cpc core would also have a high insulation resistance when being tested against another cpc core within another sheathed cable within the same bunch or enclosure?

And in the case of a sheathed cable insulating the bare cpc core, it offers protection against corrosion with a humid environment. But as previously mentioned cannot be designed to be permanantly connected to votage above 50v without another layer of insulation offering increased basic protection?

Also where a twin sheathed cable is used to supply a LV circuit to a class I accessory, a minimum size of 4mm single insulated cable has to be used as a cpc. Or it can be rewired with a twin and earth, the cpc being smaller than the live conductors. And the cpc within the sheath affording the same insulation value, and carrying a satisfactory level of fault current to disconnnect the circuit protection device, as that of the 4mm single insulated cable, except the 4mm cable would offer a lower r2 reading and potentially allowing a higher level of fault current?

The above isn't an exhaustive list, but provide some examples of a sheath offering insulation?

In the meantime I hope this explains why a cpc is bloody insulated in a sheathed cable?...

 

[GLENNSPARK]

Insulation is used as a method of basic protection, a bare cpc is insulated in a sheathed cable due to the nature of its design and manufacture, and remains insulated until terminated or damaged, if it wasn't it would be exposed and causing further exposure to the inner single insulated cores. You would also be able to measure a potential difference between a live conductor and the cpc within a sheathed cable if it wasn't insulated?

The cpc core would also have a high insulation resistance when being tested against another cpc core within another sheathed cable within the same bunch or enclosure?

And in the case of a sheathed cable insulating the bare cpc core, it offers protection against corrosion with a humid environment. But as previously mentioned cannot be designed to be permanantly connected to votage above 50v without another layer of insulation offering increased basic protection?

Also where a twin sheathed cable is used to supply a LV circuit to a class I accessory, a minimum size of 4mm single insulated cable has to be used as a cpc. Or it can be rewired with a twin and earth, the cpc being smaller than the live conductors. And the cpc within the sheath affording the same insulation value, and carrying a satisfactory level of fault current to disconnnect the circuit protection device, as that of the 4mm single insulated cable, except the 4mm cable would offer a lower r2 reading and potentially allowing a higher level of fault current?

The above isn't an exhaustive list, but provide some examples of a sheath offering insulation?

In the meantime I hope this explains why a cpc is bloody insulated in a sheathed cable?...

again....sheathing is not classed as insulation....its there to provide a degree of mechanical protection to the insulated cores underneath!!!
further more you still have not explained why the CPC is not insulated on flat twin....have you...
and theres a very good reason for it.....

 

[chilliwilly]

again....sheathing is not classed as insulation....its there to provide a degree of mechanical protection to the insulated cores underneath!!! WELL I NEVER!!! Mind you the trouble is though, by default it insulates the bare cpc ? Even though not designed for that purpose, as WE ALL KNOW.But does offer a degree of protection against corrosion?

further more you still have not explained why the CPC is not insulated on flat twin....have you... But if it was insulated, it could be used as a 3 core like the flex in this thread?

But as it isn't insulated, and doesn't require insulation as it isn't a live conductor, it can't be used as a live conductor can it?

That reminds me, I'm going to send my fluke multi tester back, there must be something wrong with it, everytime I try to measure volts to earth between live and the pvc sheath of a twin and earth, it displays 0 volts?

But when I measure between the cpc terminal with the cpc of the same cable, it measures a voltage?

Come to think of it, measures a voltage between live and anything with an earth potential? But not on PVC or any other material used for insulating electrical conductors?

I'm going to send it back, I can't believe I paid all that money for it and it has an intermittent fault? Come to think of it, they all have the same fault, every meter and tester I've had has had the same fault for nearly 40 years? I can't understand it?

In fact, the same thing happens when I test for voltage between live and the pvc sheath of an armoured, an FP, a flex, a porcelain pillar, a porcelain sink and bath, a pvc matt on a chacker plate gantry, an insulated enclosure, plastic conduit and trunking, and some other thingys, oh I nearly forgot... and the air?

And I think that's it without taxing my brain.

Maybe you know what could be wrong with my meters?

 

[GLENNSPARK]

again....sheathing is not classed as insulation....its there to provide a degree of mechanical protection to the insulated cores underneath!!! WELL I NEVER!!! Mind you the trouble is though, by default it insulates the bare cpc ? Even though not designed for that purpose, as WE ALL KNOW.But does offer a degree of protection against corrosion?

further more you still have not explained why the CPC is not insulated on flat twin....have you... But if it was insulated, it could be used as a 3 core like the flex in this thread?

But as it isn't insulated, and doesn't require insulation as it isn't a live conductor, it can't be used as a live conductor can it?

That reminds me, I'm going to send my fluke multi tester back, there must be something wrong with it, everytime I try to measure volts to earth between live and the pvc sheath of a twin and earth, it displays 0 volts?

But when I measure between the cpc terminal with the cpc of the same cable, it measures a voltage?

Come to think of it, measures a voltage between live and anything with an earth potential? But not on PVC or any other material used for insulating electrical conductors?

I'm going to send it back, I can't believe I paid all that money for it and it has an intermittent fault? Come to think of it, they all have the same fault, every meter and tester I've had has had the same fault for nearly 40 years? I can't understand it?

In fact, the same thing happens when I test for voltage between live and the pvc sheath of an armoured, an FP, a flex, a porcelain pillar, a porcelain sink and bath, a pvc matt on a chacker plate gantry, an insulated enclosure, plastic conduit and trunking, and some other thingys, oh I nearly forgot... and the air?

And I think that's it without taxing my brain.

Maybe you know what could be wrong with my meters?[/QUOTE]



not what you stated at #2

clearly you didn`t...otherwise you would not have made the statement at #2 that you did

again not what you stated at #2....you implied the sheath was classed as insulation....which it isn`t...regardless of any insulating qualities it may have.....
so dont blame the tools...

i havn`t once blamed your test gear....

and you still havn`t answered the (very relevent question) i posed to you at #22 & #27 which was why does the CPC on a flat cable not have any insulation along any of its length?
nearly 40 years in the game....you should know then.....
i suspect you dont....
answer today please

 

[Darkwood]

you quoted para.2 of the reg. i was referring to para.1. no mention of single core in there.

I think your misinterpreting this reg first paragraph simply states that the use of green and yellow combination is exclusively reserved for earth meaning you cant mark a live/neutral with green/yellow it not mean you cant sleeve a g/y with rown or blue and alter its identity.
Having said that Ill agree its a practice I wouldn't do myself.

 

[chilliwilly]

again....sheathing is not classed as insulation....its there to provide a degree of mechanical protection to the insulated cores underneath!!! WELL I NEVER!!! Mind you the trouble is though, by default it insulates the bare cpc ? Even though not designed for that purpose, as WE ALL KNOW.But does offer a degree of protection against corrosion?

further more you still have not explained why the CPC is not insulated on flat twin....have you... But if it was insulated, it could be used as a 3 core like the flex in this thread?

But as it isn't insulated, and doesn't require insulation as it isn't a live conductor, it can't be used as a live conductor can it?

That reminds me, I'm going to send my fluke multi tester back, there must be something wrong with it, everytime I try to measure volts to earth between live and the pvc sheath of a twin and earth, it displays 0 volts?

But when I measure between the cpc terminal with the cpc of the same cable, it measures a voltage?

Come to think of it, measures a voltage between live and anything with an earth potential? But not on PVC or any other material used for insulating electrical conductors?

I'm going to send it back, I can't believe I paid all that money for it and it has an intermittent fault? Come to think of it, they all have the same fault, every meter and tester I've had has had the same fault for nearly 40 years? I can't understand it?

In fact, the same thing happens when I test for voltage between live and the pvc sheath of an armoured, an FP, a flex, a porcelain pillar, a porcelain sink and bath, a pvc matt on a chacker plate gantry, an insulated enclosure, plastic conduit and trunking, and some other thingys, oh I nearly forgot... and the air?

And I think that's it without taxing my brain.

Maybe you know what could be wrong with my meters?[/QUOTE]



not what you stated at #2

clearly you didn`t...otherwise you would not have made the statement at #2 that you did. I said and I quote..."But certainly not a cpc within a twin and earth cable, as it would only be single insulated and carrying a voltage over 50 volts and not satisfying basic protection". Just in case you didn't understand the anecdote which is swinging toward being an ironic comment.I was refering that if the cpc was used as a live conductor, it would be equivilent to single insulated, if you don't agree with that fact, then please explain why you wouldn't be making contact with a live part if you touched the sheath?

again not what you stated at #2....you implied the sheath was classed as insulation....which it isn`t...regardless of any insulating qualities it may have.....
so dont blame the tools...

i havn`t once blamed your test gear.... I never said you did, I asked you if you knew what was wrong with them, as I couldn't get a reading when testing between live and the sheath covered cpc, and you haven't answered the question?

and you still havn`t answered the (very relevent question) i posed to you at #22 & #27 which was why does the CPC on a flat cable not have any insulation along any of its length?
nearly 40 years in the game....you should know then.....
i suspect you dont....
answer today please

Its so that cheese makers can rub the cheese against the cpc and make gorgonzola and stilton, its been proved its a much more energy efficient and environmently friendly way of making it. Infact they're getting an increase in their rebate from the carbon trust.

And when the circuits are run at low level, it also helps to stop losses arising from slugs and the like from squirming further up the wall and onto the shelves and eating the cheese.

The trouble is though, there could be a departure from reg 514.4.2 paragraph 3, but hey what's a departure in the case of such beautiful flavoured cheese? At least there won't be any slug trails on it.

Hope this answers your question?

And I hope I answered it in the time limit you asked for?

Cheers.

Thanks for coming.

 

[stuartcourt]

WOW that was trippy

 

[GLENNSPARK]

well...i have to say..you really have put a smile on my face there chilli....
the answer your looking for is that the CPC is not insulated so it will intercept any fault (the reason it runs between the live conductors) before any fault has a chance of going down any penetrations (screws, nails & the like)...which could be the case if it was insulated...

 

[stuartcourt]

nothing to do with cheese then, (no course not)

 

[chilliwilly]

What if the penetration was at the side and through a live core, or even between 2 of the cores used as live of a 3 core and earth?

That is the whole point of of reg 522.6.6.

I hope that reason for not insulating the cpc is only relevent for the cheese factory.

 

[GLENNSPARK]

What if the penetration was at the side and through a live core, or even between 2 of the cores used as live of a 3 core and earth?

That is the whole point of of reg 522.6.6.

I hope that reason for not insulating the cpc is only relevent for the cheese factory.

yep...and thats the chance you take....but the explanation i gave you for the CPC not being insulated was correct....
i dont do fiction...

 

[chilliwilly]

God help us, or at least the folks who you have wired up.

 

[GLENNSPARK]

God help us, or at least the folks who you have wired up.

lol....
now, i distinctly remember a thread you put up ...when you first showed up in here...
there you were goin on about putting lighting and power on one circuit...with no mention of fusing down for the lighting portion...
dont you dare deny it....you said it...
oh and by the way....i know what i`m doing fella when it comes to the things i`v `wired up`....lol...

 

[GLENNSPARK]

remember the rods one you came out with as well....
`oh just stick a rod in the ground...see what happens`...lol...had to pull you up over that as well....and not just me...but Mr. earthing and bonding himself had something to say over it.....lolffs....lol...

 

[GLENNSPARK]

God help us, or at least the folks who you have wired up.

i also think that you know underneath i am aware of disconnection times..so stop being silly now...

 

[PEG]

That was fiesty! the last time folk battled that hard over the earth,rubber boats were bouncing off Japanese whalers...:45:

 

[bigbaddave]

Ahh man... have i missed the crack

 

[chilliwilly]

GLENNSPARK.

And I will carry on wiring radials in hopscotch fashion serving more than one floor and one room, and when the rating of lighting accessories is improved to match the rating of power outlets, I will also include wall lights and maybe even centre lights on the same circuit. So there still will be lights and power in the event of a fault on one floor and in one room. And watch this space, this will become the norm across Europe including the UK.

I will carry on using one or more earth spikes to obtain a ze reading or as a permanent method of providing a TT installation in the absence of a main earth. No matter what the type of supply, and what the other bloke says.

I'm glad that you remembered (but then again how could someone like you forget?), but you will also remember that I didn't and won't stand corrected about my methods by you or anyone else who dare not leave their comfort zone of limited experience.

Only if and when my customers, the consultants that I work with, and the niccy ever have any issues with my methods, only then will I stand corrected. After all why should I stand corrected to the likes of you? They are the ones who use my services and have done for a few years, and are coming back to using them since starting up again.

And don't worry, in the unlikely event of any of my customers ever having the misfortune of phoning you, especially domestic ones, there will be as fitted drawings present along with the circuit schedule. So you won't look too stupid not knowing how to extend a radial circuit that covers both floors and including bedrooms. But then again summing you up, you would probably walk away and tell them it needs a rewire because it doesn't have ring mains, and has one or more earth spike because there is a TN supply with no main earth because the area board/DNO won't come and connect one.

But you can always tell them that the cpc in the twin and earths within the fabric of the building and elsewhere, mean that they can drive a nail into them and still be safe no matter how its wired. As safe as the MPs daughter who allegedly were killed from driving a nail through a cable and we all know the rest.

EDIT: Another outburst like that will get your account removed.

 

[Darkwood]

Now now boys play nice or you won't be able to stay out late .

Chilly to note suggested language as such will see you banned its a public forum for all ages and experiences and just because your having anger management issues doesn't mean you have to show them on here.. there is more than one way to make your point that don't flout the rules of the forum.

We all have different working methods but follow the same set of rules although some specifics of the regs can be interpreted different ways.

A few pointers here ....the outer sheath of T7E provides environmental protection and shouldn't be implied that its their for insulation or for mechanical protection ...it is there for environmental protection of which affords it a level of mechanical protection and insulation amongst other things like UV, chemical and oil resistance but as the amount of this protection goes it could be a very low level hence its misleading to say its their for that particular strength.

Also the earth in a T & E is bare IMHO to increase the chances of a fault occurring if the outer sheath and inner insulation is breached... Water ingress is then more likely to create a fault, overheating of the cable is more likely to short out before a fire situe' as the insulation perishes it is adjacent to a bare earth, and also the most widely used domestic wire it brings down costs as their is no real need to insulate it at extra cost when you opposition undercut you on price and leave it un-insulated. Yes it can be breached/damaged without faulting and creating a potentially dangerous situe but the regs are in place to keep such issues to a minimum they cant be totally irradicated
but the chances of it occurring can.

 

[stuartcourt]

Time to close this thread I believe nothing constructive here

 

[telectrix]

there is a simpler explanation as to why the cpc in T/E is not insulated. the cable is first constucted as twin, with a small aperture down the middle for the lenght of the cable, usually 100m. now, if the cpc was insulated, how in hell could the manufacturers push it all in?

 

[Badged01]

Simple Tel, just make the hole bigger!

 

[BigSi]

I just popped back after a few busy days at work to see how my thread was doing........errrrr, I’ll get my coat!!!

 

[SPARTYKUS]

I just popped back after a few busy days at work to see how my thread was doing........errrrr, I’ll get my coat!!!

Thats funny!

 

[Spudnik]

Well, just to add to the debate, i was taught to never use the cpc (in flex) as a live conductor, which i am most happy with.

As for the CPC in twin and earth, i understand the reasons for it being un sheathed, is that its not a current carrying conductor, plus the cost of manufacture.

And i also seem to remember that any cable should have an earth conductor present, and connected, but obviously not to DI accessories.