Ungrounded Conductors From Same Circuit on Same Breaker?

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Rick Christopherson said:
If they were electrically joined at both ends, then the current entering and leaving the shared nodes would be equal. Electrically joined at both ends does not mean you can have an entire circuit's worth of conductors in the middle and still be electrically joined. You can't ignore all of the nodes in the middle and call that a single conductor.
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We will have to disagree on that.

I see nothing in that NEC section that speaks of current or nodes.

Only electrically joined at each end and in the case of a ring circuit they are. (IMO)
 
iwire said:
They are joined at each termination and the fact it is a circle or ring means there are all electrically joined at each end (IMO)
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Ok Bob, let's go back to where someone was talking about an unbroken conductor feeding a number of devices.

Imagine both ends of a single conductor are landed on the same breaker, this can not be "conductors in parallel" as it is physically one continuos piece of wire that starts and stops at the same place, would this be a violation of the NEC wording?

Roger
 
roger said:
Ok Bob, let's go back to where someone was talking about an unbroken conductor feeding a number of devices.

Imagine both ends of a single conductor are landed on the same breaker, this can not be "conductors in parallel" as it is physically one continuos piece of wire that starts and stops at the same place, would this be a violation of the NEC wording?

Roger
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IMO no, it is not per the NEC, that is a conductor, not multiple conductors. Cut the same wire once and IMO they suddenly do become parallel conductors.

I fully agree that both examples are the same electrically but they are not the same NEC wise. (IMO)
 
iwire said:
IMO no, it is not per the NEC, that is a conductor, not multiple conductors. Cut the same wire once and IMO they suddenly do become parallel conductors.

I fully agree that both examples are the same electrically but they are not the same NEC wise. (IMO)
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What allows you to ignore one wire nut but not another? If you cut the wire, you cut the wire. You want to ignore all cuts but one so you can call it parallel. If your argument is that you can call several wires connected together with wire nuts as one single conductor, then the entire ring is one single conductor, as Roger pointed out.
 
Rick Christopherson said:
. If your argument is that you can call several wires connected together with wire nuts as one single conductor, then the entire ring is one single conductor
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No I am not saying that, I saying if it was a single conductor it would not be in parallel to the NEC but when terminate at each device it is not a single conductor it is a number of conductors. A number of conductors that when connected in a loop become parallel conductors under the NEC description.


I am saying ..... put aside your years of training, all your knowledge of circuits and just apply only what the NEC says.
 
iwire said:
They are joined at each termination and the fact it is a circle or ring means there are all electrically joined at each end (IMO)
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But thats not what the NEC says. It says at "Both ends" not "each end." There is not two ends (electrically joined) to the circuit in question.
 
iwire said:
No I am not saying that, I saying if it was a single conductor it would not be in parallel to the NEC but when terminate at each device it is not a single conductor it is a number of conductors. A number of conductors that when connected in a loop become parallel conductors under the NEC description.
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And what about the example that was brought up earlier where a single conductor was run in a loop, insulation was removed at locations along the circuit and conductors were spliced off the loop conductor to run to devices? The original circuit was never cut so it is still a single conductor. Is it parallel.

iwire said:
They chose the word 'electrically' not the word 'physically'. Had they said 'physically' joined at both ends I would clearly agree with many of the others that the conductors in a ring circuit would not be considered parallel conductors by the NEC.
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I think you are misinterpreting "electrically joined" vs. "physically joined." Lets assume they had used the word "physically." If we had parallel conductors (in the conventional sense) running between two busses, where the conductors were attached to the busses with individual lugs, then these conductors would not be "physically" joined. The conductors would not have any physical contact with each other, but would clearly be parallel in the sense that the NEC intends.
 
david luchini said:
And what about the example that was brought up earlier where a single conductor was run in a loop, insulation was removed at locations along the circuit and conductors were spliced off the loop conductor to run to devices? The original circuit was never cut so it is still a single conductor. Is it parallel.
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I already explained my position on that when Roger asked me.

As long as it is one, uncut conductor it does not match the NEC description of parallel.



I think you are misinterpreting "electrically joined" vs. "physically joined."
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Regardless of what they may have meant it says what it says, electrically joined and in a ring circuit they are electrically joined at each end. (IMPO)

Furthermore ......... if we do start trying to guess what the intent is ......... I feel the intent would be to disallow a ring circuit.
 
iwire said:
. . . it says what it says, electrically joined and in a ring circuit they are electrically joined at each end.
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Not in the context of 310.4, not as that article is written. If you cannot add the ampacity of one conductor to the ampacity of another conductor, and get a higher total ampacity, then the two conductors are not "electrically joined at each end." I proved that in post #137.
 
iwire said:
Furthermore ......... if we do start trying to guess what the intent is ......... I feel the intent would be to disallow a ring circuit.
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No, if we were discussing "intent" we wouldn't even be having this discussion, because the "intent" is to ensure that no single conductor in a parallel arrangement can exceed its amperage rating. Since no conductor in this circuit is sized smaller than the OCPD, this isn't even on the table.
 
Rick Christopherson said:
No, if we were discussing "intent" we wouldn't even be having this discussion, because the "intent" is to ensure that no single conductor in a parallel arrangement can exceed its amperage rating.
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I think you are guessing that is the only intent.

If that was the only intent I see no reason for (a) of this exception.

Exception No. 1: Conductors in sizes smaller than 1/0
AWG shall be permitted to be run in parallel to supply
control power to indicating instruments, contactors, relays,
solenoids, and similar control devices, or for frequencies of
360 Hz and higher, provided all of the following apply:

(a) They are contained within the same raceway or
cable.

(b) The ampacity of each individual conductor is sufficient
to carry the entire load current shared by the parallel
conductors.

(c) The overcurrent protection is such that the ampacity
of each individual conductor will not be exceeded if one
or more of the parallel conductors become inadvertently
disconnected.
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charlie b said:
Not in the context of 310.4, not as that article is written. If you cannot add the ampacity of one conductor to the ampacity of another conductor, and get a higher total ampacity, then the two conductors are not "electrically joined at each end." I proved that in post #137.
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Where is the rule that says conductors in parallel must add to the ampacity?
Again I point to exception that tells us small conductors may be run in parallel but the individual conductors must have an capacity that exceed the OCPD.
 
iwire said:
I think you are guessing that is the only intent.

If that was the only intent I see no reason for (a) of this exception.
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No, I am not guessing at the intent. It is quite clear. Citing an exception to infer intent is a flaw in logic, especially when that exception is referring to something like Control circuits. You're really reachin', Bob. :p :D
 
iwire said:
Where is the rule that says conductors in parallel must add to the ampacity?
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If they are in parallel, then their ampacities will add. That is the very reason we are allowed to put power conductors in parallel in the first place. That is the very purpose of 310.4.
iwire said:
Again I point to exception that tells us small conductors may be run in parallel but the individual conductors must have an capacity that exceed the OCPD.
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And I reply that they don't want us to take advantage of the increased ampacity for the control circuits addressed by that exception, because the conductors are smaller and more likely (than a 1/0) to be damaged.
 
charlie b said:
If they are in parallel, then their ampacities will add. That is the very reason we are allowed to put power conductors in parallel in the first place. That is the very purpose of 310.4.

No, the exception proves that section is about more than increasing ampacity.

And I reply that they don't want us to take advantage of the increased ampacity for the control circuits addressed by that exception, because the conductors are smaller and more likely (than a 1/0) to be damaged.
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And we are discussing conductors in sizes 14 and 12 as far as I know.


Rick Christopherson said:
No, I am not guessing at the intent. It is quite clear. Citing an exception to infer intent is a flaw in logic, especially when that exception is referring to something like Control circuits. You're really reachin', Bob. :p :D
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No I am not reaching, sorry if it does not fit your expectations.

The fact that exception is about control circuits is irreverent to the discussion at hand.


Engineers, is there anything they cannot complicate. :D
 
Really, guys. Do any of you honestly think that anyone's opinion of what 310.4(A) says or means is going to be changed by any of this haranguing? Looking for all this hidden meaning, you'd think it was the Da Vinci Code instead of the NEC we were dissecting. To me, the language is clear and simple. The line feed conductors are not electrically joined at both ends because there is non-trivial resistance between the points where they touch the ring. But more importantly, they are not joined because one end is over here and the other is over there. Whether the wire is cut at the connection points is the reddest of herrings; it has nothing to do with anything.

But does any of this splitting of already many times split hairs have any significance to any of us in real life?

The authors of the Code are accessible, why not just send one of them an email and ask them what they meant? Or is it that it's more fun to argue ad nauseum about what the meaning of the word "is" is?
 
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How far back until the last time the wording of 310.4 has been changed? (I really don't know I am asking, and I am asking about the wording, not any moving of sections without changing anything else in case that has happened)That is the time period when you need to find the authors from.

Here is an a drawing of an example charlie b posted in post #137. If conditions are right in theory you can balance it and call it 100% parallel. That doesn't make it ok with 310.4 though.

ring_parallel.jpg


When it comes to conductors and terminations there is resistance that happens there. That is why each section of a parallel conductor needs to have same characteristics so that each section has equal resistance and divides the current equally. In the "ring" circuit the conductors are parallel to each other from the source to the "middle" of the ring, but each side does not have even sections of wire, splices, or whatever else is "electrically joined together", and is not necessarily loaded evenly either causing more unbalance of the parallel path.

I have asked why and so has Bob, if this is not installing conductors in parallel then why do we even need exception 1 to 310.4(A)? Control circuits have lots of parallel paths to achieve the desired logic sometimes, and they do not normally carry any significant amount of power, it only makes sense for those reasons to allow parallel paths in those type of circuits.
 
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