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Discussion Starter · #1 ·
I'm looking for a NEC reference that allows 1 neutral sized for the unbalanced load to take the place of running 6 or 8 neutrals back to the load center. NEC 200.4 talks about multi circuit and 215.4 talks about enclosure but I don't see a "no you can't do it."
anyone have experience with this? :)
 

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200.4 is it


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 un-
grounded feeder conductors unless specifically permitted
elsewhere in this Code.


Each neutral/grounded conductor is only allowed to supply 1 circuit, multiwire circuit, or set of feeders
 

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Well there's 220.61 if we're talking feeders or services

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.

EDIT: Sorry I misread the OP. You're talking about a "super neutral" which is prohibited. I was talking about sizing the neutral for the calculated load.
 

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Discussion Starter · #4 ·
thx's,
200.4 has a couple exceptions 3-4 and 5 wire shared neutral.
erics37 never seen a "super neutral" gotta code referencez?
 

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thx's,
200.4 has a couple exceptions 3-4 and 5 wire shared neutral.
erics37 never seen a "super neutral" gotta code referencez?
What you are describing here:

...1 neutral sized for the unbalanced load to take the place of running 6 or 8 neutrals back to the load center...
Would be a super neutral.

If, for instance, you had like eight 120 volt circuits in a conduit (derated properly of course), instead of running 8 individual neutrals back (or 4 if they were MWBCs on a single-phase service), you ran a single equivalent extra-size neutral to carry that load, that'd be a super neutral and would be prohibited.

Of course if you're running 8 circuits in a conduit you might be better off running a feeder and setting a subpanel or something.
 

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Discussion Starter · #8 ·
ya eric37 thats what I've done... in the past no problem with inspection, used this method to bridge between old and new load centers, where the old is turned into a splice box but this time AHJ is questioning the method... he wants individual neutrals... we don't agree. maybe I'm being stubbern seems to me NEC isn't saying this method can't be used.
300.3(B)4 allows enclosures to include neutral termination
215.4(A) common neutrals
200.4 exception 1 grouped in raceway
looked extensively through the book of no's (NEC) haven't found a definative answer. :blink: thx
 

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ya eric37 thats what I've done... in the past no problem with inspection, used this method to bridge between old and new load centers, where the old is turned into a splice box but this time AHJ is questioning the method... he wants individual neutrals... we don't agree. maybe I'm being stubbern seems to me NEC isn't saying this method can't be used.
300.3(B)4 allows enclosures to include neutral termination
215.4(A) common neutrals
200.4 exception 1 grouped in raceway
looked extensively through the book of no's (NEC) haven't found a definative answer. :blink: thx
I don't have the code references, but in the past the "super neutral" was allowed. That was changed in one of the recent code changes and it's no longer an accepted practice.
 

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I'd have to ask what code cycle you are currently under?

2008 doesn't contain a 200.4, much less an exception. 2011 does, but it doesn't have an exception. As, Techy stated earlier, 200.4 is the reference that you cannot do it.

Section 215 is for feeders so that wouldn't apply to your situation.

You might be able to convince someone with 300.3, but you would need to install a gutter between the panels. Then you still would have to deal with the listing of the old panel. When we use old panels as JBoxes, we have to remove all the guts. I'm imagining you are leaving the neutral bar and the connections to that neutral bar. We wouldn't have that option.
 

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ya eric37 thats what I've done... in the past no problem with inspection, used this method to bridge between old and new load centers, where the old is turned into a splice box but this time AHJ is questioning the method... he wants individual neutrals... we don't agree. maybe I'm being stubbern seems to me NEC isn't saying this method can't be used.
300.3(B)4 allows enclosures to include neutral termination
215.4(A) common neutrals
200.4 exception 1 grouped in raceway
looked extensively through the book of no's (NEC) haven't found a definative answer. :blink: thx
Your AHJ is right unless you're in an older NEC, as others mentioned. And techy gave you the code reference way back in post #2. It's pretty cut and dried.

The 200.4 exceptions in the 2014 NEC have nothing to do with a super neutral. "Grouped in raceway" means that if you have a conduit with several circuits coming through it (several hots and several neutrals) then you need to group them together so you know which neutral goes with which hot, unless such grouping is inherently obvious.

You might be able to reduce your number of neutrals to the new panel by making some into multiwire branch circuits.
 

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Discussion Starter · #12 ·
I'm using 2014 code.
the AHJ is looking at another job today so i'm going with the 300.3, the conduit routing is really close to the discription in that NEC section. its worth a try :rolleyes: otherwise its after closing night work. thx for all the input:no:
 

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I'm using 2014 code.
the AHJ is looking at another job today so i'm going with the 300.3, the conduit routing is really close to the discription in that NEC section. its worth a try :rolleyes: otherwise its after closing night work. thx for all the input:no:
:laughing::laughing:

Well if you can warp reality like that and talk a guy into letting you commit a code violation, then more power to you :thumbup: You should be a politician!
 

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Prior to 200.4 in the 2011 code it was the code making panel's opinion that the specific "shall be permitted" wording in 215.4 and 225.7(B) that permitted a "common" neutral acted to prohibit all other uses of a "common" neutral. In the 2011 code cycle they were convinced that a specific permission to do something does not act to prohibit you from doing something else and they accepted the proposal that resulted in 200.4 being added to the 2011 code.
 

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Interesting that your code has moved to ban it, whereas the super neutral is specifically made legal in the CEC. I've never seen one before though. Was it common to install a super neutral while it was still legal?

4-026 Common neutral conductor
Provided that when in metal enclosures all conductors of feeder circuits employing a common neutral are
contained within the same enclosure, a common neutral shall be permitted to be employed for
(a) two or three sets of 3-wire, single-phase feeders; or
(b) two sets of 4-wire, 3-phase feeders.
 

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Interesting that your code has moved to ban it, whereas the super neutral is specifically made legal in the CEC. I've never seen one before though. Was it common to install a super neutral while it was still legal?

We have a similar exception.


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.
(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 conductor shall be en-
closed within the same raceway or other enclosure as re-
quired in 300.20.



But this is only allowed for 'Feeders', Not 'Branch Circuits' which is typically what you'll see.
 

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There is a conduit that comes into my dwelling from the street to my meter/main socket. It has a super neutral in it. Sometimes the actions of the code panels disturbs me a bit. What actual problem has been encountered with the use of superneutrals? (assuming proper sizing was used in the installation)

I do believe that apprehension and dread run rampant in them thar scientific code making panels some days............
 

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Interesting that your code has moved to ban it, whereas the super neutral is specifically made legal in the CEC. I've never seen one before though. Was it common to install a super neutral while it was still legal?
I used to spec them all the time in the mid to late 90s for energized furniture (cubicles). I'm not sure why it's such a big deal now -- as long as your neutral is 200%, you can never have an imbalance that exceeds that on a 3 circuit multibranch -- you'll always be limited to 173% worst case (sqrt 3) on a 3 phase system.
 

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There is a conduit that comes into my dwelling from the street to my meter/main socket. It has a super neutral in it. Sometimes the actions of the code panels disturbs me a bit. What actual problem has been encountered with the use of superneutrals? (assuming proper sizing was used in the installation)

I do believe that apprehension and dread run rampant in them thar scientific code making panels some days............
Your service neutral isn't a super neutral, unless you've got a half dozen or so paralleled hots from each leg coming in to your house.

But I see where you're coming from.
 

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The only way I have heard the term "super neutral" used, prior to this thread was for a neutral that was up-sized on a wye system because of possible harmonic currents.

I had never heard that term used for a neutral that was being used with two of more ungrounded conductors that are on the same leg or phase.
 
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