Nec 2011 200..4 VS 215.4(A)

[Dennis Alwon]

200.4 Neutral Conductors. Neutral conductors shall not be used for more than one branch circuit, for more than one multiwire branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this Code.

This article is clear in saying that one grounded conductor for one feeder unless specifically allowed elsewhere.

215.4 Feeders with Common Neutral Conductor. (A) Feeders with Common Neutral. Up to three sets of 3-wire feeders or two sets of 4-wire or 5-wire feeders shall be permitted to utilize a common neutral

This article seems to allow it. Is this not negating the other section on feeders? Also what are 4 or 5 wire feeders? Is that just more than one per phase or what?

 

[infinity]

200.4 says "unless specifically permitted elsewhere in this Code". 215.4(A) would be one place, 225.7(B) would be another.

 

[Dennis Alwon]

200.4 says "unless specifically permitted elsewhere in this Code". 215.4(A) would be one place, 225.7(B) would be another.

So why even include it if it is okay to do. Not sure 225.7 is saying the same.

It just seems 200.4 say no good and 215.4 says it is okay.

 

[infinity]

So why even include it if it is okay to do. Not sure 225.7 is saying the same.

It just seems 200.4 say no good and 215.4 says it is okay.

Prior to 2011 use of a common neutral was permitted in 215.4 and 225.7 but there was no specific prohibition for using a common neutral in, for example, a home run with 6 circuits and one over-sized neutral. The 2011 now specifically address the 6 circuit example by prohibiting it but still allows the other two installations 215.4 and 225.7 as it always has.

It was Don's proposal that was accepted.

_______________________________________________________________
5-49 Log #3644 NEC-P05 Final Action: Accept in Principle
(200.8 (New) )
_______________________________________________________________
Submitter: Donald A. Ganiere, Ottawa, IL
Recommendation: Add new text to read as follows:
200.XX Common Neutral Conductors. Common neutral conductors shall not
be used unless specifically permitted elsewhere in this code.
Substantiation: It appears that CMP 2 is attempting to prohibit the use of
common neutral conductors by specifically permitting them in 215.4(A) and
225.7(B). There is no reasonable reading of the words “shall be permitted” that
can lead the code user to the conclusion that these words actually prohibit the
use of common neutral conductors in other cases. The act of specifically
permitting something in no way prohibits something else. Section 3.1.2 in the
NEC Style Manual says that the words “shall be permitted” are to be used to
permit an alternate installation method. The words “shall not” are required to
be used to prohibit an installation method per 3.1.1 of the Style Manual. This
change will make the wording in 215.4 and 225.7 comply with the style
manual rules. Also the prohibition of the use of common neutrals should rest
with CMP 5 as they have control of Article 200, Use and Identification of
Grounded Conductors and not with CMPs 2 and 4.
Panel Meeting Action: Accept in Principle
Revise the recommendation to read:
200.4 Neutral Conductors. Neutral conductors shall not be permitted to be
used for more than one multiwire branch circuit or for more than one set of
ungrounded feeder conductors unless specifically permitted elsewhere in this
Code.
Panel Statement: CMP-5 revised the proposal to more specifically apply to
multiwire branch circuits and feeders.
Number Eligible to Vote: 16
Ballot Results: Affirmative: 16
Comment on Affirmative:
JOHNSTON, M.: Continue to accept this proposed revision as amended by
the action of CMP-5. This additional section provides clarity to users about
how neutral conductors should be used and coordinates with the newly defined
terms neutral conductor and neutral point. Additional uses of the term common
conductor are not necessary and the NEC should migrate to removal of the
term as it is undefined and can cause inconsistency in enforcement.

 

[Dennis Alwon]

So why allow it for feeders but not branch circuits? Again what is a 5 wire feeder?

 

[jumper]

So why allow it for feeders but not branch circuits? Again what is a 5 wire feeder?

Maybe one of those wierd 2 phase systems? IDK.

220.61 Feeder or Service Neutral Load.
(A) Basic Calculation. The feeder or service neutral load
shall be the maximum unbalance of the load determined by
this article. The maximum unbalanced load shall be the
maximum net calculated load between the neutral conductor
and any one ungrounded conductor.
Exception: For 3-wire, 2-phase or 5-wire, 2-phase systems,
the maximum unbalanced load shall be the maximum net
calculated load between the neutral conductor and any one
ungrounded conductor multiplied by 140 percent