No it isn't.It is a bad question
No it doesn't.and, in addition to the fact that it has two correct answers,
No it isn't.It is a bad question
No it doesn't.and, in addition to the fact that it has two correct answers,
If you were to believe that D was the correct answer and you really did bother to spend half of your day talking to someone one the phone who will probably have no idea what the hell a bonding cable is, let alone what size it should be and they then tell you that they are not aware of any such requirements, what are you going to do next?
The only people claiming that it is are the ones who can't read the question and/or the regs properly.
It's not a question of precision, it's a question of what gets you to the conductor csa.Just because answer B might convey a more precise answer does not mean that answer D is, in itself, incorrect.
Because D is not what the regulations say (remember what the exam is).The course of action specified in answer D is a necessary part of following the more detailed course of action set out in answer B (assuming that the latter is taken as as following the note to the table, and not just the actual tabulated figures). So how can answer D possibly be incorrect?
Possibly.If there are two correct answers and the format of the exam requires that only one answer be provided as the "proper" answer, then it's a very badly worded question/answer set.
You couldn't.The supply undertaking's requirements can override the minima specified in the table, as acknowledged by the note to that table. So how could you possibly know whether such overriding requirements exist in any particular case without contacting the supplier?
Presumably it depends upon impedances and therefore the distributor's estimate of the worst-case current that could flow to (a very low impedance) earth from their neutral cable under fault conditions.Just as a side note (which, I imagine, shouldn't take too long to get a clear answer )
Under what circumstances would a Local Distributor require a larger main protective bonding conductor?
No - you'd not be able to do that, because that's Answer B, and you've already rejected that as wrong.If you were to believe that D was the correct answer and you really did bother to spend half of your day talking to someone one the phone who will probably have no idea what the hell a bonding cable is, let alone what size it should be and they then tell you that they are not aware of any such requirements, what are you going to do next?
Use the minimum size specified in the table, because you've consulted the supply undertaking and have been told there is no requirement to use a larger size.
How can looking at the relevant table be the right thing to do if you've rejected that by saying that the answer "look at the table" is wrong?The question in the exam is about what BS7671 requires, and as the note to the relevant table makes clear, BS7671 requires that you consult the supply undertaking to see if the minimum size in the table is satisfactory or not.
Stop trying to wriggle out of it.So yes, answer B is correct if choosing the size in accordance with table 54.8 and its associated note is what answer B means.
Answer D is "Contact the DNO". AND THAT IS ALL THAT ANSWER D DESCRIBES DOING.But that does not mean that answer D is wrong,
It's not a question of more detail, it's a question of what the regulations tell you to do.Answer B might give a course of action which goes into more detail,
Unless the regulations tell you to only contact the DNO then Answer D is wrong.but that doesn't make answer D wrong per se.
If you want to cavil about the exact words used then please go ahead.Does BS7671 require consultation with the supply undertaking in order to decide the size of the conductor?
I think I probably should give up Completeness and Correctness are two totally separate issues. The (correct) answers to a high proportion of questions are 'incomplete', in that it's very often possible to qualify those answers in some way, but that does not make them 'incorrect'.If it's incomplete it cannot be correct.Yes, it's incomplete, but it's still correct.
In that case, B is also incorrect since, as you have written yourself (in very large letters) the implicit requirement to consult the supply undertaking is an 'integral part of' Table 54.8, hence an integral part of answer B....since BS 7671 does not require consultation with "the supply undertaking" then D can't be correct.
So therefore, B is the only correct answer. B tells you to look at 54.8, D does not.If you were to believe that D was the correct answer and you really did bother to spend half of your day talking to someone one the phone who will probably have no idea what the hell a bonding cable is, let alone what size it should be and they then tell you that they are not aware of any such requirements, what are you going to do next?
Use the minimum size specified in the table, because you've consulted the supply undertaking and have been told there is no requirement to use a larger size.
Not really, but it wasn't mean't to be. I wrote that to provoke a bit of practical thought and comparison about the process of following the routes of B and DYes, we know that calling the DNO is likely to be a fruitless exercise and you could quite easily spend the whole afternoon on the phone and still not talk to somebody who even understands your question. But that's not really the point, is it?
Indeed, so again, B is the only way to find the answer. If you believe D is correct but the Local Distributor do not have any special requirements, then you do not know the required cable size.The question in the exam is about what BS7671 requires, and as the note to the relevant table makes clear, BS7671 requires that you consult the supply undertaking to see if the minimum size in the table is satisfactory or not.
The guidance suggested by answer D is not incorrect, as you say. However, in terms of the question, D does not in itself get you the answer if the Local Distributor says "no special requirements" so cannot be correct.So yes, answer B is correct if choosing the size in accordance with table 54.8 and its associated note is what answer B means. But that does not mean that answer D is wrong, because in any event it's necessary to carry out the course of action mentioned in answer D in order to carry out the course of action required by answer B. Answer B might give a course of action which goes into more detail, but that doesn't make answer D wrong per se.
The only people claiming that it is are the ones who can't read the question and/or the regs properly.
Does BS7671 require consultation with the supply undertaking in order to decide the size of the conductor?
If it's incomplete it cannot be correct.Yes, it's incomplete, but it's still correct.
No it doesn't.The question therefore has two 'correct' answers
It's not a question of precision, it's a question of what gets you to the conductor csa.
B does, in an unqualified way.
Without qualification, D does not.
There's also the small matter that the regulations inform you that B is the right answer, not D.
So you'd contact the supplier, which is what you should glean from reading Table 54.8.
No - you'd not be able to do that, because that's Answer B, and you've already rejected that as wrong.
The note is not "associated with Table 54.8".
IT IS AN INTEGRAL PART OF TABLE 54.8
The regulations do not tell you to only contact the DNO.
Because since BS 7671 does not require consultation with "the supply undertaking" then D can't be correct.
Does BS7671 require consultation with the supply undertaking in order to decide the size of the conductor?
No, it doesn't
Presumably it depends upon impedances and therefore the distributor's estimate of the worst-case current that could flow to (a very low impedance) earth from their neutral cable under fault conditions.Just as a side note (which, I imagine, shouldn't take too long to get a clear answer )
Under what circumstances would a Local Distributor require a larger main protective bonding conductor?
However, maybe I'm missing something, but what may be a bit silly about all this is that, in practice, it could well be the impedance of the connection to earth via supply pipes etc. is usually going to be the main determinant of the current flowing from neutral supply to that earth under (supply) fault conditions, more-or-less regardless of the CSA of the neutral supply conductor. The figures in Table 54.8 require an MPB with a current-carrying capacity of roughly half that of the neutral supply conductor, which means that, ultimately, the MPB would melt before the supply neutral if the impedance of path to earth via the MPB was sufficiently low to result in a current of 'melting' potential - which I somewhat doubt would be the case.
Kind Regards, John
By simply reading what is there to be read.Does BS7671 require consultation with the supply undertaking in order to decide the size of the conductor?
No, it doesn't
How do you figure that?
I noticed thatWe've just been talking about the very note in table 54.8 which requires it.
I noticed thatWe've just been talking about the very note in table 54.8 which requires it.
Very well - if you can't see that a procedure which when completed does not guarantee that it will produce a result when a result is needed cannot be the correct procedure to follow then I'll give up trying to explain such a fiendishly difficult concept to you and concentrate on something you might be able to cope with.Being incomplete does not make it incorrect.
Multiple choice exams like that do not have more than one correct answer to each question. That's not how they work, and you really ought to know that.If there are two answers, neither of which is incorrect, then both of those answers must be correct. The only issue is whether one is more precise than the other, not whether one is wrong.
Do the regulations tell you that where PME conditions apply the main bonding conductor should be determined after consultation with the supply undertaking AND NOTHING ELSE?Yes, answer B gives you the route to the actual stipulated size. But you need to do the things set out in answer D in order to follow the route of answer B. Answer D cannot, therefore, be wrong as such.
Do the regulations tell you that where PME conditions apply the main bonding conductor should be determined after consultation with the supply undertaking AND NOTHING ELSE?Do you have to consult the supply undertaking in order to decide upon the conductor size stipulated by BS7671? Yes. So answer D cannot possibly be incorrect, even if it does not give the full story.
Do the regulations tell you that where PME conditions apply the main bonding conductor should be determined after consultation with the supply undertaking AND NOTHING ELSE?So if one can use such a term, answer B might be "more correct," but that doesn't make answer D wrong.
Nobody who understands perfectly could possibly select the wrong answer.It's still a very badly worded set of answers if it can result in somebody providing a perfectly correct answer and failing to get a mark for that question, even though he understands perfectly what is required.
You have.Who's rejected it as wrong?
That's not possible because the multiple choice question does not work like that.That's the whole point being made here: There is no one correct answer out of the four options provided. Two of them are correct, just to differing degrees.
Do the regulations tell you that where PME conditions apply the main bonding conductor should be determined after consultation with the supply undertaking AND NOTHING ELSE?Doesn't alter the fact that answer D is still correct.
Do you select the size in accordance with table 54.8, including the note which says you must check with the supplier? Yes. So answer B is correct.
Do you select the size after consulting with the supply undertaking? Yes. So answer D is also correct, even though by itself it does not lead you directly to the actual size you need.
D gets you ONLY contacting the DNO, AND NOTHING ELSE.No, but they do require you to contact the DNO, which is what answer D says. So how can answer D be wrong?
I don't want to argue that at all.But BS7671 does require such consultation. You've just said so - It's in the note with table 54.8. Unless you still want to try and argue that just because BS7671 does not use those two precise words that they somehow don't count.
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