Lectrician, thank you. A viable answer with a reference,
Which reference?
Was it this one:
WESTIE - It most definantly does not comply with BS7671 for direct burial, or burial in plastic duct.
No - can't be, because you'd known that (and had actually had the actual reference) since Page 1.
Was it this one:
Your neutral is earthed, as expected, but we cannot use a neutral "as an earth" - If we could, we would be running two core cables everywhere, and not twin and earth or 3 core flex for appliances etc. WE HAVE to keep our neutral and earth seperate.
No - can't be, because John and I had told you that several times - in fact. as John pointed out
I've merely been saying, repeatedly, exactly what you have now thanked Lectrician for saying!
without resort to veiled insults or shouting.
Well - I don't know where the "veiled insults" came from - I can't see any here.
I will own up to shouting, and do you know why?
I guess what they mean is that the cable will not come to any harm by being buried.
But that's not the same as meaning that it complies with BS 7671 if directly buried. It doesn't matter what the maker says about the tolerance of his cable to the environmental conditions, nor what installations which are not required to comply with BS 7671 can have - the point is that if you want to comply with BS 7671 you may not use it directly buried.
Just read 522.8.10 - there's no doubt.
522.8.10 (page 101) : “Except where installed in a conduit or duct which provides equivalent protection against mechanical damage, a cable buried in the ground shall incorporate an earthed armour or metal sheath or both”.
So where does this state that a cable buried directly must have an earthed armour?
Concentric cables compy with ESQCR by having an earthed metallic sheath so why does it not comply with BS7671
No-one said that it had to have earthed armour - as you quote, it has to have earthed armour or an earthed metallic sheath. The question is whether (in the 'mind' of BS7671), outer conductors of concentric cable which are connected to the installation's neutral constitute an 'earthed metallic sheath' - and, as I have said, I personally very much doubt that, particularly in the case of split con (and BS7671 effectively bans straight con within installations).
No one doubts that plain con is not allowed to be used other than on the supply network.
I ask again, as split con complies with the metallic sheath requirements of ESQCR, why does it not comply with BS7671?
As I keep saying if it constitutes an earthed metallic sheath in one piece of legislation there is no reason why it shouldn't in another document, whilst legislation can often be strange it would be rare and fly in the face of those that are employed to ensure such differences don't occur.
I think it can, and does, because after the cutout N does not count as an earthed conductor - indeed there are almost universally mandated protective devices which will cut off the supply should you earth it.
So no - for electrical installations within the scope of BS 7671, split-con does not have an earthed metallic sheath.
It still does not change the fact that the neutral is connected to earth and is usually at or about earth potential!
So because there is some vague wording and some liability driven thinking it suddenly changes!
Bear in mind that this cable type has been in use for over 40 years and is surrounded by an earthed metallic sheath as is required by law!
You'll be arguing that black is white next.
It still does not change the fact that the neutral is connected to earth and is usually at or about earth potential!
No, it doesn't change that and, as I said, it is not primarily an engineering issue we are talking about. We're talking about regulations.
However, as I was suggesting before, do you really think that BS7671 would be satisfied if one 'earthed' exposed-conductive-parts to the neutral conductor (and, indeed, perhaps took the next logical step and 'did without' a CPC altogether)?
Electrically I would not disagree!
A definition of earthed that is used is "connected to the greater mass of earth"
If that is accepted then a neutral conductor in an installation is connected to the greater mass of earth by virtue of its connection to the supply network.
(This is assuming that there is no automatic device to disconnect the neutral without disconnecting the live as well)
Face it, on a PME system there is live and neutral/earth, just by calling them neutral and earth/cpc either side of the cut-out doesn't change what is connected to what
Nor does it change the fact that the ESQCR prohibit consumers from combining the neutral and protective functions in a single conductor in their installations.
Therefore the neutral of a split-con cable cannot, no matter what potential it is at wrt earth, be regarded as an earth.
The neutral of a split-con cable is not suitable for use as a protective conductor because the law prohibits us from using it as one.
You may not use split-con cable where the cable is required to have an earthed metallic sheath.
I'm sorry if that causes you any distress, and I can assure you I'm not arguing that black is white.
But it's what the regulations say.
But it's what the regulations say.
Which specific regulation says specifically that
Err - I'd already answered that on Page 1.
You may not use split-con cable where the cable is required to have an earthed metallic sheath.
(bearing in mind that as far as ESCQR is concerned you can!
I suspect it is more a case of not wanting too than can't as regards BS7671
It doesn't cause me any distress at all BTW. I am happy to see any opinion but have yet to see any specific fact
Electrically I would not disagree! A definition of earthed that is used is "connected to the greater mass of earth" If that is accepted then a neutral conductor in an installation is connected to the greater mass of earth by virtue of its connection to the supply network. Face it, on a PME system there is live and neutral/earth, just by calling them neutral and earth/cpc either side of the cut-out doesn't change what is connected to what
As I said before, 'electrically' I would not disagree very much, either - but we are talking about 'the regulations' (specifically, about BS7671).
However, to repeat my question, do you really believe that 2-core fixed wiring, with the neutral regarded as acting as the 'CPC' (and therefore used to 'earth' exposed-conductive parts) in a TN-C-S installation would be regarded by anyone (on the consumer's side of the meter) as being BS7671-compliant?
As has been pointed out (and we know anyway) it is specifically prohibited
If you accept that BS7671 prohibits the combining of neutral and earth/CPC functionality in a single conductor (hence also, by implication, prohibiting the 'earthing' of anything by connecting it to the {'separate} neutral conductor), why do you think BS7671 would regard a sheath as 'earthed' if a discrete part of it was the neutral conductor, rather than a separate 'CPC'?
Not just BS 7671.
See
8(4).
As we know that it is compliant with ESQCR I am at a loss to understand the supposed lack of compliance with BS7671, it does not appear to be specifically stated anywhere (or if it is the reference hasn't surfaced) that it does or does not comply but is a matter of various opinions.
And there stands my argument the cable has been used for 40 years on networks and complies.
And yes - at this point I shouted.
On Page 1 I had told you which BS 7671 regulation required an earthed metallic sheath (or armour).
But at least twice you said that you'd not seen any reference to that here.
You claimed that split con must be OK because the neutral is connected to earth and therefore it could be said to have an earthed metallic sheath, and yet on several occasions, including two explicit references to a specific ESCQR regulation it had been pointed out to you that in consumer installations, i.e. installations within the scope of BS 7671, connecting the neutral to earth was forbidden.
In post #2227043 you agreed that you (and "we") all knew that combining neutral and cpc in a single conductor was prohibited.
You had known from Page 1 that BS 7671 required the earthed metallic sheath to be suitable for use as a protective conductor.
So you had known all along that the neutral conductors in split-con were not suitable for use as a protective conductor.
And then after 2 people had reiterated the prohibition of CNE, and John wrote this:
If you accept that BS7671 prohibits the combining of neutral and earth/CPC functionality in a single conductor
Not just BS 7671. See
8(4).
Indeed - but what westie does not seem to accept is that there is a problem (at least in terms of BS7671) if half the sheathing (which is required to be 'earthed') of a cable is connected to neutral, rather than earth. To my mind, that constitutes using the neutral for a 'protective function' - hence, as you imply, seemingly non-compliant with ESQCR as well as BS7671.
you wrote
As we know that it is compliant with ESQCR I am at a loss to understand the supposed lack of compliance with BS7671, it does not appear to be specifically stated anywhere (or if it is the reference hasn't surfaced) that it does or does not comply but is a matter of various opinions.
And there stands my argument the cable has been used for 40 years on networks and complies.
So yes, I shouted.
Because
for
page
after
page
you
had
not
been
hearing
anything
people
were
telling
you.
... I told you that the basis of 'what we were arguing about' was quite simple! Are there any electricians out there who would be happy to bury split con (without any protection) and call it BS7671-compliant?
