Poll - Ring final circuits with high integrity earthing

[EFLImpudence]

I thought I hadn't made that many mistakes.

 

[SimonH2]

So is that a yes or no to the question ?

Since you seem so determined to miss the point (or are unable to grasp it) I'll give you a very precise answer to that.

543.7.1.203(iii) requires two circuit protective conductors and those two conductors themselves individually need to meet the requirements of 543.7.1.203 which apply to circuit protective conductors.

Would you quote 543.7.1.203(iii) and highlight where it says "circuit" in "circuit protective conductor"

Do we agree that 543.7.1.203(iii) does not require either of those conductors, on it's own, to be a high integrity protective conductor as defined in 543.7.1 ?

I agree that it does not.

Thank you.

Simple questions, that have simple yes or no answers.

Only simpletons believe that "simple questions" always have "simple answers".

True, but you seem to be implying that I'm a simpleton because your statement implies you do not believe there is a simple answer. If I were to write something that appears to be deliberately implying that you are a simpleton then I think you'd probably be offended.
I don't suppose you would like to apologise for that insult ?

EDIT: So you agree that 543.7.1.203(iii) does not in any way require either of those conductors to be a ring ? Yes or No

Given that the context of this topic is "Ring final circuits with high integrity earthing", no, of course not

Thank you

 

[JohnW2]

However, what I've been describing (after my second question) could just as easily be 'the protective bits' of a ring circuit.

Yes, one ring CPC.

Those "two CPCs"

No, one if it were a ring circuit.

This is where, IMO, it becomes irrational. Before I mentioned how the L and N were arranged (as a ring or not), you (and BAS) agreed that there were two CPCs, and you will presumably both continue agreeing with that if I tell you that it is a radial circuit, with the "two CPCs" being joined at the last socket. Why do those "two CPCs" (which, together, physically constitute 'a ring') suddenly become "one CPC" if one runs L&N conductors from the last socket back to the CU?

Kind Regards, John

 

[EFLImpudence]

This is where, IMO, it becomes irrational.

That may be so but no more than why a ring circuit cpc has to be connected to the MET at both ends.

Before I mentioned how the L and N were arranged (as a ring or not), you (and BAS) agreed that there were two CPCs, and you will presumably both continue agreeing with that if I tell you that it is a radial circuit, with the "two CPCs" being joined at the last socket. Why do those "two CPCs" (which, together, physically constitute 'a ring') suddenly become "one CPC" if one runs L&N conductors from the last socket back to the CU?

Because it is configured to the requirements of a ring circuit cpc.

Which of these meets the requirements of A horseshoe?

 

[JohnW2]

It also satisfies 543.2.9, because by joining those two CPCs at the socket (every socket), one has created a ring.

And that's where everything falls apart for you, with a ring circuit. ... You have, as you say, created A ring CPC. In the singular. One ring. You have created a single CPC which complies with 543.2.9. 543.7.1.203(iii) requires that you have two individual ones, so you are no longer in compliance with that.

This is where we disagree. What constitutes "A CPC" is defined in Part 2, which does not have a separate or different definition for "A ring CPC', and the definition of "A CPC" does not alter because of any regulations. If there are two 'sets of components' each of which qualifies as "A CPC" before they are joined, they can still be regarded as two CPCs when their ends are joined together - and that remains true regardless of how the L and N conductors in the circuit are arranged.

I know you aren't interested in the application of common sense to this situation but, if you were, you would probably see that 543.7.1.203(iii) is calling for two independent paths from each socket to earth, whilst 543.2.9 is (for whatever reason - as I previously suggested, possibly Zs considerations) calling for the protective conductors in any ring final to be arranged as a ring. Both of those requirements are satisfied by a 'standard' ring final (with a single CPC ring), leaving only 543.7.1.204 ('separate terminals') to be satisfied for the circuit to qualify as HIE ... but that's merely common sense (and what, I suspect, virtually everyone believes and does), so you will want to stick with your view of what the regulations "actually say".

As I've said before, your whole position is based on the belief that a standard ring final (with 'separate' terminals') is not already "HIE" (as a radial with 'separate terminals' becomes after its single CPC has been turned into a single CPC ring) - whereas I believe differently.

Kind Regards, John

 

[JohnW2]

This is where, IMO, it becomes irrational.

That may be so but no more than why a ring circuit cpc has to be connected to the MET at both ends.

Well, for a start, I'm not sure that one irrationality can be used to justify another! As I've said before, I agree that it's not obvious why there is a requirement for a ring final to have a ring CPC, but I suspect it may be a practical issue in terms of Zs. With 2.5mm² cable on a B32, one could not have a very long circuit if the CPC were connected to the MET only at one end.

Which of these meets the requirements of A horseshoe?

That's not really an appropriate analogy, since, unlike the CPC situation, there is no situation is which either of the two halves could be described as "a horseshoe!

Kind Regards, John

 

[EFLImpudence]

Your view may very well be all that is required to achieve HIE for a ring circuit but it is not what the regulations say - for whatever reason(s).


I may very well judge that a 8.5kW shower will be alright on a 30A BS3036 fuse but it is not what the regulations state.
Therefore I have to do something else.

That's not really an appropriate analogy, since, unlike the CPC situation, there is no situation is which either of the two halves could be described as "a horseshoe!

Fair enough...
.., but the point is that joining the two halves become one shoe.

 

[JohnW2]

Your view may very well be all that is required to achieve HIE for a ring circuit but it is not what the regulations say - for whatever reason(s).

You (and BAS) are talking as if the regs were well-written, unambiguous and crystal clear - in which case there would be no scope for discussion or debate - but there has been pages and pages of it! For example, just a short list in the regs of examples of the most common circuit arrangements which were acceptable as "HIE" would avoid the need for all this discussion/debate/uncertainty/whatever!

I'm sure I must have asked before, but don't recall getting an answer - if a customer asked you to install an HIE ring final circuit, what would you do? Would you really install two independent CPC rings, 'walk away' from the job, or what?

I may very well judge that a 8.5kW shower will be alright on a 30A BS3036 fuse but it is not what the regulations state. Therefore I have to do something else.

Yes, but that's very different. In that case the regs are clear as to what is required, even if you personally think (maybe even 'know'!) that no harm would come from 'overloading' the fuse to that small extent for short periods of time. I am not attempting to 'over-ride' clear regulations - I am attempting to decide what unclear regulations "say", or are trying to say. Unsatisfactory, I know, but if the regs are unclear and even those who (jointly) publish them are "not authorised" to give advice on interpretation of them, what else can one do?

That's not really an appropriate analogy, since, unlike the CPC situation, there is no situation is which either of the two halves could be described as "a horseshoe!

Fair enough... ... .., but the point is that joining the two halves become one shoe.

Yes, but we haven't been talking about joining "two halves of a CPC" to make "one CPC" - we're talking about joining "two CPCs" and ending up with "one CPC" - the mathematical corner of my mind would be happy with "½ + ½ = 1", but is less happy with "1 + 1 = 1"

Kind Regards, John

 

[EFLImpudence]

...

 

[EFLImpudence]

OK

 

[EFLImpudence]

I'm sure I must have asked before, but don't recall getting an answer -

You didn't.

if a customer asked you to install an HIE ring final circuit, what would you do? Would you really install two independent CPC rings, 'walk away' from the job, or what?

Obviously I never have but as with other rings I would install a radial.

I am attempting to decide what unclear regulations "say", or are trying to say. Unsatisfactory, I know, but if the regs are unclear and even those who (jointly) publish them are "not authorised" to give advice on interpretation of them, what else can one do?

Even when unclear, it comes down to how you and I interpret them.
You are using your knowledge and judgement and deciding what you think is right. I am reading them and interpreting what they (actually) say.

 

[JohnW2]

I'm sure I must have asked before, but don't recall getting an answer -

You didn't.

Lies ....

I am hesitant to vote (other than no) as .....

That's all true ..... If you are still undecided, what about turning it into a practical question - if a customer asked you to install a ring final circuit with high integrity earthing (the implication being that it should be regs-compliant), what would you do? I somehow doubt that you would install two separate CPC rings, or run a 10mm² CPC ring, would you?

if a customer asked you to install an HIE ring final circuit, what would you do? Would you really install two independent CPC rings, 'walk away' from the job, or what?

Obviously I never have but as with other rings I would install a radial.

I'm not sure I fully understand that but, per my question, what would you do if the customer specifically wanted a ring final - walk away?

Even when unclear, it comes down to how you and I interpret them.

Of course - hence the extensive discussion!

You are using your knowledge and judgement and deciding what you think is right.

No - at least not primarily. If we were talking about views, based on knowledge and judgement, as to what would be electrically 'sensible'/'right'/adequate for HIE, I suspect that you and I, and probably even BAS, would essentially agree. What I am actually doing is try to use my knowledge and experience of reading, backed up by underlying knowledge about the electrical principles involved, to try to make a judgement about what the regulations are "saying", or trying to say.

I am reading them and interpreting what they (actually) say.

With respect, I think that what both you and BAS are doing is interpreting what you believe they are saying, or trying to say.

Kind Regards, John

 

[ban-all-sheds]

Would you quote 543.7.1.203(iii) and highlight where it says "circuit" in "circuit protective conductor"

543.7.1.203 The wiring of every final circuit and distribution circuit intended to supply one or more items of equipment, such that the total protective conductor current is likely to exceeed 10mA, shall have a high integrity protective connection complying with one or more of the following:-

(i)...

(ii)...

(iii) Two individual protective conductors, ...

Are you going to claim that if it says a circuit must have a protective conductor, that that is not a circuit protective conductor?

True, but you seem to be implying that I'm a simpleton because your statement implies you do not believe there is a simple answer. If I were to write something that appears to be deliberately implying that you are a simpleton then I think you'd probably be offended.
I don't suppose you would like to apologise for that insult ?

Is it an insult?

Do you really believe that just because you can write what looks like a simple question there has to be a simple answer?

Go on - answer the simple question "When did you stop beating your wife?"

EDIT: So you agree that 543.7.1.203(iii) does not in any way require either of those conductors to be a ring ? Yes or No

Given that the context of this topic is "Ring final circuits with high integrity earthing", no, of course not

Thank you

You do realise that I was saying "no, of course not" to your question "So you agree that....", and not "no, of course 543.7.1.203(iii) does not in any way require either of those conductors to be a ring"?

 

[EFLImpudence]

I'm sure I must have asked before, but don't recall getting an answer -

You didn't.

Lies ....

I meant - you didn't get an answer.
You must learn to read what's written.

I'm not sure I fully understand that but, per my question, what would you do if the customer specifically wanted a ring final - walk away?

Well, that's just asking the same question about what is a compliant ring.
Why would they insist on a ring?
I've never had to do it.
Anyway, two cpcs. The easiest way is four core, isn't it?
2.5 3C+E doesn't meet the csa requirements so 2.5 4C flex?
It would depend on the situation, though, wouldn't it.

]With respect, I think that what both you and BAS are doing is interpreting what you believe they are saying, or trying to say.

Yes, obviously and I believe that is what is written.
I don't otherwise see how 543.2.9 and 543.7.1.203(iii) can both be met with one 1.5mm² CPC.

 

[ban-all-sheds]

Why do those "two CPCs" (which, together, physically constitute 'a ring') suddenly become "one CPC" if one runs L&N conductors from the last socket back to the CU?

Because by running the L&N conductors back to the CU you have turned the circuit into a ring, and therefore created the need for the CPC to be a ring. So what had been a ring remains a ring. What had been a compliant HI protective connection for a radial (a CPC returned to the CU, thus forming a ring) does not remain a HI protective connection for a ring, because that needs two separate ring CPCs.