phase a, phase a , and neutral ?

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Think of it like this: A feeder to a 200 amp panel has a grounded conductor and 2 ungrounded conductors, properly sized, that feed all individual branch circuits that are on the "A" phase. Is this a problem. The only difference is the OCPD in line with the hots. If I directly wired them to the feeders they would function fine except for the lack of OCPD.
 
The problem isn't about whether it will work or not. I think we all understand it will work, and we understand the possibility of overloading the neutral if the neutral isn't increased in size.

The issue is: does the code allow A-A-Neutral as a branch circuit or a feeder?

Because of 215.4, I am led to believe that the NFPA intends that A-A-Neutral is illegal. Otherwise, why even bother with 215.4?

I haven't seen anything that literally makes a properly sized branch circuit with A-A-neutral illegal though. But it sure throws some wickets into 210.19 though.

Say we had 2 A phase breakers and a shared neutral feeding convenience outlets. Someone care to give the code section that describes how to size the neutral?
 
Why would you want to do it in the first place? This installation does not meet the definition of a multiwire branch circuit. Art. 100.

Regardless, If the load cannot exceed the conductors' ampacity and the neutral is a #12 for example, you can not have more than a 20 (actually less) amp load combined total on the breakers. If you are limited to that, then why not just use 1 breaker? If you need more than 20 amps use 2 phases and make it a multiwire branch circuit, or install larger conductors and a breaker with a higher rating.
 
crossman said:
We aren't arguing those points either. You are correct.

We are simply discussing whether or not the NEC specifically prohibits such an installation.
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That was kind of obvious too, but I didn't address it because I don't beleive the NEC should attempt to ban every bad install idea as they are infinite. Even is this could be done legally there is no benefit to doing it this way if they use a #8 neutral, for example. It would make a good extra credit question for appentices.

Bottom line, see Art 90.1(A&B).
 
crossman said:
The issue is: does the code allow A-A-Neutral as a branch circuit. . . ?
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I am going to take the stance that it is not legal, and that the existing code language explicitly prohibits it. Well, perhaps not that explicitly, but I think the prohibition is there. It is a bit of a stretch, perhaps, but I think my position is defensible. I need to take care here, because I have been proven wrong twice recently, and I can't afford another strike. ;) :grin:

Here goes:

Start with Article 100, but not in the definition of MWBC. Instead, start with the definition of "branch circuit." You will note that it speaks of the overcurrent device in the singular. A thing can only be called a "branch circuit," if it has a single overcurrent device. It can be a MWBC and still have more than one overcurrent device (because that term is defined separately), but it cannot be just a "branch circuit."

Please correct me if I am wrong about this, but I don't think anyone makes a single overcurrent device that uses two or more connections to the same phase (e.g., Phase A and Phase A). So a "circuit" that has a breaker on Phase A and another breaker also on Phase A is not a "branch circuit," by definition.

Next, go to 210.2, and we see, "Branch circuits shall comply with this article." Since an A-A-N set of wires would not comprise a "branch circuit," it would not comply with the article.

Within the article, in 210.4, it explicitly states that "Branch circuits recognized by this article shall be permitted as multiwire circuits." We have already had discussions of that definition, and we have agreed that an A-A-N set of wires would not be a MWBC.

I base my statement that this proposed configuration is not allowed on the assertion that it is not a MWBC, and that it is not a BC, and therefore it does not comply with the 210.2 requirement that it follow the article.
 
2-280 Log #2224 NEC-P02
Final Action: Reject​
(215.4)___________________________________________________________
Submitter:
Donald A. Ganiere, Ottawa, IL
Recommendation:
Revise as follows:
215.4 Feeders with Common Neutral.

(A) Feeders with common Neutral Two or three sets of 3-wire feeders or two​

sets of 4-wire or 5-wire feeders shall be permitted to utilize a common neutral.

(B) In Metal Raceway or Enclosure. Where installed in a metal raceway or
other metal enclosure, all conductors of all feeders using a common neutral
shall be enclosed within the same raceway or other enclosure as required in
300.20.​
Substantiation:
There is no code violation in using a common neutral so the
specific provision to use one is not required.
Panel Meeting Action: Reject

Panel Statement:
The panel disagrees with the submitter?s substantiation.
Section 215.4 (A) is the requirement which limits the number of feeders that


​


may share a common neutral.
Number Eligible to Vote: 12

Ballot Results:
Affirmative: 12
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My proposal called for the text shown in red to be deleted. I do not agree with the panel's action. There is no way, from a legal or enforcement point of view, that the words "shall be permitted" act to prohibit other installations. We have the same issue in 310.4 where the code trys to use the words "shall be permitted" to prohibit the paralleling of conductors smaller than 1/0. I had a proposal for that section that was also rejected.​


(310.4)
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Submitter: ​



Donald A. Ganiere, Ottawa, IL

Recommendation: ​

Revise as follows:​



310.4 Conductors in Parallel. Aluminum, coper-clad aluminum, or copper


conductors of size 1/0 AWG and larger size #1 AWG and smaller , comprising

each phase, polarity, neutral, or grounded circuit conductor, shall be permitted

to not be connected in parallel (electrically joined at both ends).
Substantiation:
There is no code rule that prevents the installation of
conductors smaller than 1/0 AWG in parallel in the current code. The existing
rule just specifically permits the use of conductors 1/0 and larger in parallel,
but does not prohibit smaller conductors from being paralleled.​
Panel Meeting Action: Reject

Panel Statement: The present language meets the requirements of Section
3.1.3 of the NEC Style Manual. Article 310.4 permits conductors 1/0 or larger
to be installed in parallel. The general rule is that conductors sized smaller than
1/0 are not permitted to be run in parallel.​
Number Eligible to Vote: 11

Ballot Results: Affirmative: 11

​


​


​
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The style manual clearly says that the "shall be permitted" can be used to act as an exception to a rule. Where are the rules that say you can't use a common grounded conductor or that you can't parallel conductors smaller than 1/0?
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Charlie B., I love your logic, and was going along the same lines as for looking at the definitions of BCs and seeing if it somehow prohibited the A-A-neutral installation.

When I read your post, I thought "Beautiful! Charlie nailed it!"

But, on further inspection, according to the definition of "Branch circuit", the grounded conductor is actually not a part of the branch circuit.

And everyone else, don't shoot me, I am just the messanger. Read the definition. Only the ungrounded conductor is considered as a branch circuit.

Edit: typo
 
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Don, thak you for giving us insight on those proposals and the thoughts of the CMPs. I found that interesting for sure, and I am in agreement with you and with your wording of the sections.
 
crossman said:
Read the definition. Only the ungrounded conductor is considered as a branch circuit.
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What does the word, "between," as used in that definition, mean to you? Does it mean, "electrically connected from one point to another"? Or perhaps does it mean, "physically routed from one location to the other"? ;) :roll: :smile:
 
charlie b said:
Please correct me if I am wrong about this, but I don't think anyone makes a single overcurrent device that uses two or more connections to the same phase (e.g., Phase A and Phase A).
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Okay, consider yourself corrected. :smile: You're describing a tandem breaker.
 
charlie b said:
What does the word, "between," as used in that definition, mean to you? Does it mean, "electrically connected from one point to another"? Or perhaps does it mean, "physically routed from one location to the other"? ;) :roll: :smile:
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I'm going with your first option, as evidenced by this drawing which appears in the "Crossman's 2008 NEC Handbook".:roll:


111111111.jpg


Honestly, I always figured the neutral was part of the branch circuit, but as long as we are playing with the literal meaning of the text in the code, may as well take it as far as we can!:smile:
 
Added thought: If "between" is used as "physically between" insted of "connected between", then what if I run a phone line physically between where the breaker is and where the outlet is? So the phone line is a branch circuit?

11111.jpg


Okay, bad example. How about other neutrals in the panel in the same pipe... other hot wires? Physically routed between?
 
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LarryFine said:
Okay, consider yourself corrected. :smile: You're describing a tandem breaker.
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It's happened before. :cool: But the only ones I have seen were separate breakers, two of which could be put into the same space as a single, "normal size" breaker. Are you saying that there are "tandem breakers" that share a single overcurrent device, but that supply separate loads? I am not asking about two breaker handles in a single case, for that IMHO would comprise two breakers, and could not, therefore, supply a single "branch circuit."
 
crossman said:
How about other neutrals in the panel in the same pipe... other hot wires? Physically routed between?
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They would not be going from and to the same locations.

By the way, I appreciate the handbook image, but I don't rely on any handbook as a source authority for resolving any code-related discussions.
 
charlie b said:
By the way, I appreciate the handbook image, but I don't rely on any handbook as a source authority for resolving any code-related discussions.
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I understand, but for me, I always consider the source of the reference before I deem it useless and cast it aside. That Crossman's Handbook is damned reputable, let me tell you.
 
crossman said:
That Crossman's Handbook is damned reputable, let me tell you.
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I'll take your word on that, never having seen a copy myself. But that is not relevant to what I said. My point was that it is not the "source authority," meaning that it was not written by the people who wrote, reviewed, debated, voted on, and ultimately published the code. It can be, at best, one person's (or group's) opinion on another person's (or group's) intentions. So if you wish to offer evidence that supports your point of view on a code question, I will pay more attention if you cite the code itself, or cite one of the documents that was published during and concerning the code review process.
 
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