BS7671 says: where an installation comprises more than one final circuit, each final circuit shall be connected to a separate way in a distribution board.
So would this not be two final circuits?
EFLImpudence - court, yes I know, very unlikely
Definition of 'new circuit' (new notifiability - England)
- Thread starter JohnW2
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BS7671 says: where an installation comprises more than one final circuit, each final circuit shall be connected to a separate way in a distribution board.
So would this not be two final circuits?
EFLImpudence - court, yes I know, very unlikely
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And in fig 15a, it says:
A ring final circuit starts and finishes at the distribution board where it is connected to a 30a or 32a over current protective device
A ring final circuit starts and finishes at the distribution board where it is connected to a 30a or 32a over current protective device
We've debated this a lot. The main problem with a 'figure of 8' circuit is that it presents a testing nightmare; electrically, there are quite a few arguments in favour of it. However, Simon was not talking about a 'figure of 8' circuit.
Well, this is where my interpretation may be regarded as some by a little silly, because if there were a new (additional) MCB, I would say that (by applying BS7671 definition) it would be a 'new circuit'.
Kind Regards, John
Not if you accept the definition in Part 2 of BS7671, which says that an assembly of equipment protected by the same overcurrent protection device is 'a circuit', not 'two (or more) circuits'.
Would you use your argument to say that two branches of a radial circuit originating at the CU, or a spur from a ring final originating from the CU, were non-complaint, because they represented 'two circuits'?
Kind Regards, John
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True (albeit that's only 'informative'), but so what? It doesn't actually say that two ring finals couldn't start and finish at the same place, does it?
However, as I keep saying, I really don't think that Simon was suggesting that anyone would want to do this, so it's all moot.
Kind Regards, John
No, because of the specific definition of a ring final.
No, but I suppose having read the definition for a radial too, technically two branches of a radial originating at the cu wouldn't be compliant either.
But a spur from a ring final at the cu is! Some of these regs really don't make sense!
I know, and I do agree.
The fact that there is a definition of a (single, conventional) ring final circuit surely does not alter the fact that an 'unconventional' assembly of equipment protected by a single OPD is also defined as being 'a (i.e. one) circuit', does it?
Why not? Are you sure you are not basing some of your views on an assumption that things in an 'informative' Appendix of the regs are 'regulations', rather than just 'informative'?
Kind Regards, John
Yes, you are right, I was
But the definition of a ring final circuit is:
A final circuit arranged in the form of a ring and connected to a single point of supply.
Fair enough, but can one not extrapolate from that to say that a 'dual ring final' (or whatever you want to call it) would be a "final circuit arranged in the form of two rings connected to a single point of supply".Yes, you are right, I was
A final circuit arranged in the form of a ring and connected to a single point of supply.
I keep coming back to the fact that BS7671 (and maybe the Building Regs, although they don't tell us what they think!) regards any collection of wiring, accessories and equipment protected by a single OPD as being a single circuit.
Kind Regards, John
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The problem is we can't use BS7671 definitions as they would class a FCU as a new circuit. So if we can't use BS7671 definitions then it becomes a free for all.
The English language is unlike most others in that the dictionaries show how the word is used rather than what the word means.
So a word like decimate means to kill one in ten and comes from Roman times when they will kill one in ten of their troops if they did not fight hard enough.
However look in an English dictionary from 1950's and it will say get rid of 1 in 10 but look at a modern dictionary and it says to get rid of nearly everything nearly reversing the meaning.
So look up circuit and it starts and finishes in the same place so a MCB with nothing connected is not a circuit but a final ring is by definition two circuits so splitting them into two radials each with it's own MCB would not create another circuit.
What I am saying is you can't not class the FCU as a circuit then say splitting a ring into two radials is making a new circuit.
it's like the law on peanuts being ground nuts not taken from the ground which is often quoted as an example of gobbledygook.
Circuit. An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s). So in the house all electrical equipment is supplied from the DNO fuse so it is all one big circuit with sub-circuits taken from it. Unless you have solar panels.
OK before you shout I know that's not what it means. But it would be one way of interrupting it. If a FCU is a sub-circuit then why is the consumer unit not also producing sub-circuits? I think the building regulation rules on circuits are another example of gobbledygook.
The English language is unlike most others in that the dictionaries show how the word is used rather than what the word means.
So a word like decimate means to kill one in ten and comes from Roman times when they will kill one in ten of their troops if they did not fight hard enough.
However look in an English dictionary from 1950's and it will say get rid of 1 in 10 but look at a modern dictionary and it says to get rid of nearly everything nearly reversing the meaning.
So look up circuit and it starts and finishes in the same place so a MCB with nothing connected is not a circuit but a final ring is by definition two circuits so splitting them into two radials each with it's own MCB would not create another circuit.
What I am saying is you can't not class the FCU as a circuit then say splitting a ring into two radials is making a new circuit.
it's like the law on peanuts being ground nuts not taken from the ground which is often quoted as an example of gobbledygook.
Circuit. An assembly of electrical equipment supplied from the same origin and protected against overcurrent by the same protective device(s). So in the house all electrical equipment is supplied from the DNO fuse so it is all one big circuit with sub-circuits taken from it. Unless you have solar panels.
OK before you shout I know that's not what it means. But it would be one way of interrupting it. If a FCU is a sub-circuit then why is the consumer unit not also producing sub-circuits? I think the building regulation rules on circuits are another example of gobbledygook.
What about a double lollipop with one 'stick'?
If properly designed it may be better than a single but obviously one circuit.
The same for a several branch star radial.
The only difference is that the junction is not at the mcb.
If properly designed it may be better than a single but obviously one circuit.
The same for a several branch star radial.
The only difference is that the junction is not at the mcb.
I'm not going to 'shout', because I agree with you. What you're calling a 'free for all' is what I've been calling a 'grey area', where the individual undertaking electrical work has (if(s)he is concerned about 'notifiability') to make a judgement, based on his/her individual interpretation (maybe aided with discussions such as this) of the meaning of 'new circuit'.
I've made my suggestion, which seems to correspond to common sense to me. For a start, I don't think that it's sensible or helpful (in context) to regard the whole of an installation as 'one circuit' because it's all protected by the DNO fuse. Secondly, I only think in terms of 'primary' OPDs - i.e. those in CUs or switch-fuses etc. supplied directly from 'the origin of the installation' (meter in a domestic instal) - hence excluding any 'sub-circuits' potentially created by FCUs, 'sub-CUs' or whatever. That is obviously just my way of looking at it and, as you will point out, it's not exactly what BS7671 says - but it seems to make pragmatic sense. You, or others, may well have different ideas - and it's for each of us to apply whatever interpretation we feel is appropriate when deciding whether electrical work we do should be regarded as notifiable.
To be fair, decent dictionaries usually do both.
Kind Regards, John
Yep - and in all cases I would personally call it just 'one circuit'.
Kind Regards, John
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