# floating neutral



## Techy (Mar 4, 2011)

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


----------



## erics37 (May 7, 2009)

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.


----------



## pnorwil (Jan 12, 2014)

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


----------



## erics37 (May 7, 2009)

pnorwil said:


> 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:



pnorwil said:


> ...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.


----------



## Chrisibew440 (Sep 13, 2013)

That's not even a floating neutral. A floating neutral is a neutral that has not been bonded to ground.


----------



## Meadow (Jan 14, 2011)

Chrisibew440 said:


> That's not even a floating neutral. A floating neutral is a neutral that has not been bonded to ground.


Or breaks open. NEC has nothing against that unfortunetly:no:


----------



## pnorwil (Jan 12, 2014)

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


----------



## hardworkingstiff (Jan 22, 2007)

pnorwil said:


> 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.


----------



## Deep Cover (Dec 8, 2012)

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.


----------



## erics37 (May 7, 2009)

pnorwil said:


> 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.


----------



## pnorwil (Jan 12, 2014)

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  otherwise its after closing night work. thx for all the input:no:


----------



## erics37 (May 7, 2009)

pnorwil said:


> 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  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!


----------



## don_resqcapt19 (Jul 18, 2010)

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.


----------



## Vintage Sounds (Oct 23, 2009)

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.


----------



## Techy (Mar 4, 2011)

Vintage Sounds said:


> 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.


----------



## macmikeman (Jan 23, 2007)

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............


----------



## Pharon (Jan 20, 2014)

Vintage Sounds said:


> 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.


----------



## erics37 (May 7, 2009)

macmikeman said:


> 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.


----------



## don_resqcapt19 (Jul 18, 2010)

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.


----------



## Chrisibew440 (Sep 13, 2013)

I might be mistaken but however you want to interpret it is that a super neutral is just an oversized neutral and I as well have only seen it used for harmonic issues on sensitive equipment.


----------



## brian john (Mar 11, 2007)

pnorwil said:


> 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?


Why did you post FLOATING NEUTRAL? This has nothing to do with a "floating neutral" which is a common trade name for an ungrounded neutral.


----------



## erics37 (May 7, 2009)

don_resqcapt19 said:


> 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've always heard this referred to as "a neutral that was upsized 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.


That's all I've heard the term applied to.


----------



## pnorwil (Jan 12, 2014)

I agree don_ ..

this "super neutral" thing is a bit distracting. 

the heading "floated neutral" is an ungrounded wire... in a gutter/j-box/pull-box if you land a neutral it need to be floated otherwise isn't it a grounded conductor? seems obvious to me.

My AHJ and his superviser have scratched there head bald trying to come up with a reason not to allow this wiring method. for them is comes back to 200.4 even though they concede 300.4 is applicable. seems they can't get past thinking any ungrounded wire will be energyized by another neutral wire on the neutral bar or if you take the "super neutral" away all the circuits will go 240volts go figure that one.
bottom line AHJ wants me to use 200.4 wiring method.


----------



## brian john (Mar 11, 2007)

> pnorwil said:
> 
> 
> > i agree don_ ..
> ...


----------



## Pops8675 (Feb 20, 2014)

I saw what they are talking about. Found a large j-box in a refrigeration tunnel. There was a 1/0 or so neutral attached to a ground bar and all the branch circuit neutrals took off from there. Some 80' from the panel. Thought it was weird myself.


----------



## erics37 (May 7, 2009)

Pops8675 said:


> I saw what they are talking about. Found a large j-box in a refrigeration tunnel. There was a 1/0 or so neutral attached to a ground bar and all the branch circuit neutrals took off from there. Some 80' from the panel. Thought it was weird myself.


Depending on circumstances, that might be legit.

Were the phase conductors doing the same thing?

I've seen plenty of applications where there were distribution blocks stuck in a gutter with a big set of feeders landed on it and then a bunch of smaller taps coming off of it for equipment (following the feeder tap rules in Article 240).

If yours had a bunch of phase conductor branch circuits but only one big neutral conductor stuck on the bar then I'd say that yeah, it's probably a super neutral.


----------



## Pops8675 (Feb 20, 2014)

erics37 said:


> Depending on circumstances, that might be legit.
> 
> Were the phase conductors doing the same thing?
> 
> ...


No sir. The phase conductors did not do the same thing. They run through the J-box


----------



## brian john (Mar 11, 2007)

Pops8675 said:


> I saw what they are talking about. Found a large j-box in a refrigeration tunnel.* There was a 1/0 or so neutral attached to a ground bar *and all the branch circuit neutrals took off from there. Some 80' from the panel. Thought it was weird myself.


To a Ground bar or to an isolated neutral bar.


----------



## Pops8675 (Feb 20, 2014)

brian john said:


> To a Ground bar or to an isolated neutral bar.


Isolated neutral bar.


----------

