I was asked by a coworker if he could add a couple new circuits bringing the ungrounded conductor from panel "A" while terminating the grounded and EGC conductor into panel "B", which is fed from panel "A". I told him I didn't believe he could do this, that it could result in overloading the neutral between panels A and B, but can't find the code reference to back it up. 210.4(A) seems to touch on this exact subject with multiwire branch circuits, but what about 2-wire circuits? Any help would be appreciated.
Circuit conductor origination?
- Thread starter SPierce
- Start date
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kwired
Electron manager
- Location
- NE Nebraska
If anything ask how he proposes to tie the handles together so they are disconnected simultaneously.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
OP said the ungrounded conductors would come from same panel. The install is not compliant but I don't understand the handle tie thing. Nothing was said about only one neutral/ungrounded.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
And even if two hots forming an MWBC came from the first panel the handle tie could be there. Still not compliant, of course.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
That was my point in responding to kwire asking how they could tie the handles together since OP said both hots would come from the same panel.
- Location
- Massachusetts
You lost me.
If both hots come from the same panel a handle tie is easily installed and could even be required if both circuits supply a single yoke.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
See post 3, the start of this subthread.
- Location
- Massachusetts
Still lost. :?
kwired
Electron manager
- Location
- NE Nebraska
After reading OP again you are right, it appears to be single ungrounded to grounded circuit that was described with ungrounded conductor originating in panel A and the grounded conductor landing in panel
B - it did say that panel B is fed from panel A which maybe makes it a slightly more acceptable theory and good practices wise, but probably still not code wise. At some point all conductors of the same circuit will separate and you will have violation of 300.3(B) as mentioned earlier.
JFletcher
Senior Member
- Location
- Williamsburg, VA
Why would you do what OP is describing? Generator panel next to main? I dont see where 300.3B applies to panels.
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
If the ungrounded conductor for the new circuit followed the feeder from panel A to panel B, then I believe that landing the grounded and egc conductors at panel B could be compliant.
However, as in most 'could you do this completely screwy installation thought experiments', the details of getting the install compliant and safe make it likely _not_ worth the headache.
For example, the ungrounded conductor would need to be in the same conduit as the feeder if metallic conduit were used. This would mean dealing with issues of conduit fill or derating, as well as pulling this circuit conductor into the conduit in the first place.
You would have to be careful that this didn't become a 'common neutral' circuit, since that is no longer permitted.
I am sure there are other details that you would need to deal with.
-Jon
However, as in most 'could you do this completely screwy installation thought experiments', the details of getting the install compliant and safe make it likely _not_ worth the headache.
For example, the ungrounded conductor would need to be in the same conduit as the feeder if metallic conduit were used. This would mean dealing with issues of conduit fill or derating, as well as pulling this circuit conductor into the conduit in the first place.
You would have to be careful that this didn't become a 'common neutral' circuit, since that is no longer permitted.
I am sure there are other details that you would need to deal with.
-Jon
kwired
Electron manager
- Location
- NE Nebraska
May not apply to panels -but wiring methods used to get to the two panels does.
- Location
- Massachusetts
Ahh, you and smart$ extending the term 'circuit' as far as it suits.
I disagree with that approach.
IMO to the NEC a branch circuit is a sperate circuit from the feeder circuit supplying it. In other words 300.3(B) applies to the branch circuit, or the feeder circuit but not both combined.
JFletcher
Senior Member
- Location
- Williamsburg, VA
True. What I was seeing was cable (say 14/2NM) comes into panel A (main), grounding and grounded conductors terminate there, ungrounded goes thru a nipple to panel B to breaker in that panel. I *think* that is what SPierce is describing; I cant see splitting conductors of the same circuit into two panels say 60' away from each other. "couple of new circuits" would be the above repeated x times.
kwired
Electron manager
- Location
- NE Nebraska
OP said ungrounded conductor was landed in A and groounded/equipment ground in B - my guess panel A (possibly service panel) had no more room on grounded bus, and panel B was immediately adjacent but had room on the grounded/equipment grounding buses so this was fairly easy to do. Probably doesn't hurt much, but still isn't quite code compliant IMO.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Definitely don't try it with a GF breaker of any kind.
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