Dado 3 compartment or Maxi trunking - home office - use singles?

[SimonH2]

That is as easy to answer as would the question "is this a ring or a radial with parallel conductors?" be had you shown 2L and 2N connections as well.

Which is it? Please don't try to pull the wool over people's eyes by claiming it doesn't matter - you might fool some people, but not I, as I know it matters very much indeed.

No, it makes no difference whatsoever what the L&N are - please answer the simple question.
In the diagram, as drawn, is there one CPC or two CPCs - or some other answer. It's a simple question that you should have no trouble answering.

I can understand you refusing to answer it, and doing your usual diversionary tactics to obfuscate your refusal (or inability) to answer, but it does matter. How many CPCs in the diagram ?
I didn't ask anything about what regs it may or may not meet, just how many CPCs in the diagram.

 

[EFLImpudence]

543.2.9 states "THE circuit protective conductor of every ring final circuit shall also be run in the form of a ring having both ends connected to the earthing terminal at the origin of the circuit".

Simon: Are you saying this is incorrect?

 

[SimonH2]

No, I'm just trying to get BAS to answer a simple question.

 

[JohnW2]

I think somebody needs to give the IET a call!

Even the IET can only really give an 'opinion'. Although BS7671 is published partially in it's name, it's JPEL/64 who decide the content, and presumably know what their 'intent' was.

I personally think that common sense indicates what was almost certainly intended (which happens to correspond with what nearly everyone believes and does), although there clearly are at least one or two dissenting voices!

Kind Regards, John

 

[ban-all-sheds]

543.7.1.203(iii) requires two individual cpcs, each complying with the requirements of Section 543, and in Section 543, 543.2.9 requires that the cpc be in the form of a ring. So if 543.7.1.203(iii) requires two individual cpcs, each in the form of a ring, that means two individual rings.

You must be having a quiet day, since you appear to just be trying "to be clever" for the sake of it.

I have no need to try and do that.

The fact that the CPC of a ring final is required to be a the ring does not alter the fact that, when viewed from any point in the ring, there are two individual CPCs (which happen to be part of a ring) from that point back to the origin of the circuit.

No - there are two paths back to the earth bar.

But neither of those two paths is a ring.

If as you say, when viewed from any point in the ring, there are two individual CPCs, then please produce a drawing showing how, from that point, what can be viewed is two individual cpcs where each one is a ring.

I wonder if there is any number of times I can repeat, and point out, and highlight what the regulations say, before you agree that that is what they say.

543.7.1.203(iii) requires two individual cpcs. Let us call them A and B. It requires that "each comply with Section 543". What kind of reasonable meaning of everyday English words is there that you think that does not mean that A must comply with Section 543 and B must comply with Section 543?

Elsewhere in Section 543 (with which each of the two individual cpcs must comply) it says that the cpc for a ring final must itself be a ring.

So unless you want to go into Humpty-Dumpty mode with straightforward English words like "two", "individual", "each" and "both" I really don't see how you can possibly say that you are not required to have two individual rings.

In other words, a single ring satisfies all of the regulations.

No, you are wrong. How can a single ring satisfy the requirement for there to be two individual rings?

If you think you have two separate cpcs then you must be able to completely remove one separate one and have one separate one remaining. Can you do that?

Yes, as far as a particular socket is concerned, one can do that (although one would then be non-compliant with 543.2.9).

No, not "as far as a particular socket is concerned" - completely. If, whatever you do, you are not left with one cpc which still complies with 543.2.9 then clearly (surely?) you did not start out with two which complied with it.

Forget anything and everything to do with cpcs - if you have two individual things, why can you not take one away and be left with one?

If there are multiple sockets, one cannot "completely remove" one of the CPC paths (back to origin) from any but the first/last sockets - but that's because other sockets require it.

I refer you to my earlier drawings. I can completely remove one of them - either the green one or the yellow one, and be left with one which complies with 543.2.9.

That's because I started with two, as required by 543.7.1.203(iii)

 

[ban-all-sheds]

Ironically (in terms of your attempted argument), all of the methods indicated as acceptable for radial circuits [in 543.7.2.201(ii) ] amount to turning the CPC of the radial circuit into a (single) ring If that's OK for a radial, why do you imagine that two rings are needed for a ring final circuit???

Because a normal (low-integrity-if-you-prefer) radial needs a single radial cpc, and a normal ring needs a single ring cpc.

Ignoring the other methods of fatter cpcs, when HI is implemented by a different topology, a high-integrity radial needs either two radial cpcs or one ring cpc, and a high-integrity ring needs two rings cpcs.

No anomaly.

 

[JohnW2]

... a high-integrity radial needs either two radial cpcs or one ring cpc, and a high-integrity ring needs two rings cpcs. No anomaly.

No anomaly?

Kind Regards, John

 

[JohnW2]

The fact that the CPC of a ring final is required to be a the ring does not alter the fact that, when viewed from any point in the ring, there are two individual CPCs (which happen to be part of a ring) from that point back to the origin of the circuit.

No - there are two paths back to the earth bar.

... or, in slightly difference language, there are two protective conductors back to the earth bar. Are you quibbling about some perceived difference between "Protective Conductor" and "Circuit Protective Conductor"??

But neither of those two paths is a ring.

Indeed not, but when they are connected at the socket, those two protective conductors, together, become a ring.

Kind Regards, John

 

[flameport]

Ring circuits are evil and should have been deleted from BS7671 a long time ago.

 

[JohnW2]

Ring circuits are evil and should have been deleted from BS7671 a long time ago.

Some hold that view I would personally say that 'evil' is going a bit far. It's probably true that they wouldn't stand a chance of being 'accepted' if they had first been proposed in recent times - although, in fact, they are merely a manifestation of a type of diversity, a concept that is accepted (by most!) in other contexts.

In terms of the sort of thing we are talking about here, one advantage of ring final circuits is that they have CPC redundancy. This means that (unless you subscribe to the BAS viewpoint) a standard ring final circuit is well on the way to being acceptable as a HI earthing system (requiring only the 'separate terminal' addition to be fully 'HI', except for BAS) - something which is probably increasingly important as people fill up their houses with 'leaky' gizmos of one sort or another

Kind Regards, John

 

[ban-all-sheds]

Which is it? Please don't try to pull the wool over people's eyes by claiming it doesn't matter - you might fool some people, but not I, as I know it matters very much indeed.

Perhaps you can explain why you feel that it "matters very much" for a HI ring final circuit to have four paths to earth (CU/MET) from each socket (which I don't think anyone but you believes) whereas two paths (including the situation in which those two paths exist as a single CPC ring) is acceptable for a radial circuit?

My "matters very much" there was about whether the circuit Simon showed was a ring final or a radial, and it matters very much because the requirements are different.

The answer to your question is very simple, and I can give it using the concept of paths if you prefer.

Normally a radial requires a single cpc path. If it breaks then some of the sockets no longer have a cpc, and this is not allowed by the regulations. When moving to HIE, it requires two paths, i.e. twice as many (can be two radial cpcs, or, as you observe, the two paths could be provided by a ring). That improves the integrity, because a break does not leave some sockets without a cpc path. What it leaves is all of the sockets with a cpc which still complies with 543.2.9

Normally a ring final requires a single ring cpc, which as you observe does create two paths for pc current. But to comply with 543.2.9 each socket must always have those two paths because to comply with 543.2.9 you must always install the cpc in the form of a ring. If it breaks then although all of the sockets still have a cpc, they no longer have two paths because the cpc is no longer a ring, and this is not allowed by the regulations.

When moving to HIE, the circuit, just like the radial, requires twice as many paths.

That is a common sense, logical and anomaly free concept to describe as "high integrity".

I think that you are probably "really on your own" on this one, more so than ususal.

I am fully aware of that, but that is because nobody who holds the common belief does so because that is what the regulations actually say. The believe it because, for some reason, they think they should discount what the regulations actually say, and instead think they should do something different because they don't (or as this topic shows, will not) accept that the people who wrote the regulations mean what they actually say.

Let me ask you this - if you asked me to bring you "two individual pieces of rope, each of which is 5m long", and I brought you one piece, 10m long, how impressed would you be with my argument that of course I had complied with your request, because from the POV of the middle of the rope you did have 2 individual 5m pieces, one going this way, the other going that way.

If you can avoid the temptation to derail this by saying "I'd just cut it in half", I suspect you would not think that I had delivered to you the two individual pieces of rope you'd requested.

So why won't you accept what the regulations actually say?

543.7.1.203(iii) says you need two individual cpcs. Not two individual paths, two individual cpcs. Not one cpc with two paths. It says two individual cpcs.

It also says that each cpc must comply with 543.2.9. Not each path, each cpc.

543.2.9 contains a requirement for the cpc of a ring final circuit to be in the form of a ring itself. Not the path for protective conductor current, the cpc.

So if you have 1 regulation which says "this circuit needs two individual cpcs", and another which says "cpcs for ring finals must themselves be rings", HOE do you get from there to not accepting that when the circuit in question is a ring you need two individual cpc rings? Particularly when you are quite happy to accept that it does mean two individual radial cpcs when the circuit is a radial?


PS - apologies if I'm behind - I'm sure there are posts made which I've not seen, and not replied to - I will catch up when I can.

 

[JohnW2]

When moving to HIE, the circuit, just like the radial, requires twice as many paths.

That's where we disagree. As one can tell by looking at other parts of 543.7, the main concept for achieving HIE is (very reasonably) for there to be more than one path back to the CU earth bar (i.e. 'CPC redundancy'). A radial circuit does not have that, so one has to add something to make it HIE. However, a standard ring final (with one CPC ring) already has two paths, so does not need anything additional to create 'CPC redundancy' - which is presumably why 543.7.2.201(i) says that a ring final circuit is acceptable as HIE (although, again very reasonably, says that spurs of a ring final are not considered HIE, so require something additional).

In other words, a standard ring final is (give or take the 'separate terminals' requirement) HIE by design (IMO, one of the very few 'pros' of ring finals!), and therefore needs nothing more to bring it up to the same level of HIE as a radial circuit with 'the necessary additions' (or modifications).

Kind Regards, John

 

[SimonH2]

My "matters very much" there was about whether the circuit Simon showed was a ring final or a radial, and it matters very much because the requirements are different.

Ah BAS on true form, altering the question to suit his aims.
The question stands, and is really simple. For the outlet shown in the diagram, is there one CPC or two CPCs or something else ? I'm not asking whether it meets the requirements of the regulations for any specific installation, just a simple "how many ?".

 

[EFLImpudence]

My "matters very much" there was about whether the circuit Simon showed was a ring final or a radial, and it matters very much because the requirements are different.

Ah BAS on true form, altering the question to suit his aims.
The question stands, and is really simple. For the outlet shown in the diagram, is there one CPC or two CPCs or something else ? I'm not asking whether it meets the requirements of the regulations for any specific installation, just a simple "how many ?".

…but it does matter if it is a ring or radial.
Plus - in your diagram, there should be a yellow line between the socket terminals.


Geometrically speaking, would you say that a ring (circle) consists of two lines?
How many carriageways in each direction are there on the M25?

 

[JohnW2]

Ah BAS on true form, altering the question to suit his aims. The question stands, and is really simple. For the outlet shown in the diagram, is there one CPC or two CPCs or something else ? I'm not asking whether it meets the requirements of the regulations for any specific installation, just a simple "how many ?".

As I wrote yesterday, I think one of the confusions is resulting from the fact that BAS seemingly perceives a difference between "Protective Conductor" and "Circuit Protective Conductor", accepting that the former represents "A path" back to the CU (hence there are two), but regarding the latter ('CPC') as referring to the entire ring of protective conductors (with joints) - in which case there is only one. Where he got those different 'definitions' from, I haven't got a clue.

Kind Regards, John