One large neutral or many small???

[David40]

I have a service change coming up and I had an idea that could save me some work if it's not some kind of a violation. The service is on a house, meter can on the outer wall and a panel in a perpendicular wall about a foot inside. They want the new panel outside next to the meter can, so I'm going to need to LB from the new panel outside to the old panel inside and extend the circuits making the inside panel a junction box. Here is what I want to do. Instead or running a dozen #12 neutrals out to the new box I want to use a single conductor the size of the service neutral and just float the neutral bar in the old panel. That way I can avoid all those redundant splices and little pieces of wire. To me it's six or one half dozen. Is there any reason why this would be unacceptable??

Thanks for any replies.

 

[augie47]

If you are under the '11 Code, I believe that is a violation of 200.4

 

[David40]

Thanks for that reference.

 

[ceb58]

If you are under the '11 Code, I believe that is a violation of 200.4

And its tag team partner 300.3 (B)

 

[David40]

I think 300.3(B) would be a stretch because if combining the neutrals were allowed under 200 all the conductors would be in the same conduit.
The code is the code, but I'm the kind of person that like to know why of everything. I'd like to hear from an electrical engineer or scientist the reason why this should not be done. Typically your neutrals only carry the maximum imbalance on mulit-wire circuits or sets and that is why three circuits can share one neutral in a three phase configuration. I'd like to know why we can't stack as many circuits as we want as long as the neutral is large enough to handle the maximum load? Is there a legitimate reason or is this another arbitrary bureaucratic rule?

 

[petersonra]

I think 300.3(B) would be a stretch because if combining the neutrals were allowed under 200 all the conductors would be in the same conduit.
The code is the code, but I'm the kind of person that like to know why of everything. I'd like to hear from an electrical engineer or scientist the reason why this should not be done. Typically your neutrals only carry the maximum imbalance on mulit-wire circuits or sets and that is why three circuits can share one neutral in a three phase configuration. I'd like to know why we can't stack as many circuits as we want as long as the neutral is large enough to handle the maximum load? Is there a legitimate reason or is this another arbitrary bureaucratic rule?

If I had to guess, it is because someone did not like using a single conductor for the neutral and concocted a plausible reason why it was a "bad" idea.

I have never seen anything really wrong with it, and it often makes sense.

There might be some commentary on why this was changed in the 2011 code if someone knows how to find that commentary.

 

[roger]

Is there a legitimate reason or is this another arbitrary bureaucratic rule?

It is the latter. Untill the 2011 cycle there was nothing specifically prohibbiting it and there shouldn't be.

Roger

 

[David40]

I would agree.
The trend I see in the Code is to make electrical installation idiot proof. It's getting to point where you could train a monkey to wire a house. I'm surprised they haven't banned shared neutrals altogether. You would be surprised at how many so called electricians I encounter that know nothing about balancing the neutral load on multi-wire circuits. I've seen many a melted neutral simply because someone arbitrarily swapped some breakers around without taking any shared neutrals into account.

 

[ceb58]

I think 300.3(B) would be a stretch because if combining the neutrals were allowed under 200 all the conductors would be in the same conduit.

That's the point. In your OP you stated you wanted to use 1 neutral. If there were not a 200.4 300.3(B) would still not allow what you proposed.

 

[David40]

How so, I don't understand that. If I run 6 branch circuits and 6 neutrals through a conduit how is running those same 6 branch circuits and one neutral through the same conduit considered not running them in the same conduit?

 

[Dennis Alwon]

I think 210.4 comes into play also.

 

[iwire]

It is the latter. Untill the 2011 cycle there was nothing specifically prohibbiting it and there shouldn't be.

Roger

:thumbsup:

I agree on both points. If done correctly it is not a safety issue so there is no reason to prohibit it.

 

[ceb58]

How so, I don't understand that. If I run 6 branch circuits and 6 neutrals through a conduit how is running those same 6 branch circuits and one neutral through the same conduit considered not running them in the same conduit?

(B) Conductors of the Same Circuit. All conductors of
the same circuit and, where used, the grounded conductor
and all equipment grounding conductors and bonding conductors
shall be contained within the same raceway, auxiliary
gutter, cable tray, cablebus assembly, trench, cable, or
cord,

Its the wording ALL. One neutral would not be of the SAME circuit. Case in point Generac use to have one neutral for their ATS that had 10-16 circuits built in. They got called on this because of 300.3(B). They now have an single neutral for each circuit.

 

[David40]

I believe that is a mis-interpretation. The reason for keeping all the circuit conductors in the same raceway is to maintain the electromagnetic flux cancellation to avoid creating an induction choke in the line, and reduce radio frequency interference. If all the circuit conductors are in the same raceway it would not matter if there were six neutrals or one, the cancellation would still occur. The fact that we are allowed to use a single neutral in multi-wire circuits proves this.
Maybe Generac didn't use a single conductor large enough to handle the load, or more likely they pissed off some bureaucrat who used his power to retaliate and make life miserable for them.

 

[Gregg Harris]

Its the wording ALL. One neutral would not be of the SAME circuit. Case in point Generac use to have one neutral for their ATS that had 10-16 circuits built in. They got called on this because of 300.3(B). They now have an single neutral for each circuit.

300.3 (B) (4)

(4) Enclosures. Where an auxiliary gutter runs between a column-width panelboard and a pull box, and the pull box includes neutral terminations, the neutral conductors of circuits supplied from the panelboard shall be permitted to originate in the pull box.

Would'nt this contradict your interpratation of 300 (B) and in esence be what the OP wants to do with the exception of running one large nuetral conductor with the ungrounded conductors to the service panel on the outside of the house.

I do not see where it is prohibited.