While installing a neutral bus in panel B would solve one [pseudo
]problem, it may create a real problem if the panel marking says 3? 3W.I too see no problem with the install as described.
200.3
- Thread starter hassaf
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]problem, it may create a real problem if the panel marking says 3? 3W.I too see no problem with the install as described.
While installing a neutral bus in panel B would solve one [pseudo
I too see no problem with the install as described.
The name plate indicate 3ph 3w
hurk27
Senior Member
- Location
- Portage, Indiana NEC: 2008
I have always thought all conductors have to originate from the same panelboard?
210.4 address branch circuit conductors, but I can't find this for feeders?
If this is true, then the neutrals for panel C can't feed from panel A if panel C ungrounded conductors are fed from panel B?
210.4 address branch circuit conductors, but I can't find this for feeders?
If this is true, then the neutrals for panel C can't feed from panel A if panel C ungrounded conductors are fed from panel B?
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
I have always thought all conductors have to originate from the same panelboard?
210.4 address branch circuit conductors, but I can't find this for feeders?
If this is true, then the neutrals for panel C can't feed from panel A if panel C ungrounded conductors are fed from panel B?
That's true for branch circuits. You cannot connect the hot for lights or receptacle from one panel 'x' and neutral from a different panel 'y', and especially if both panels are fed separatly from a switchboard. Beacuse you can turn panel 'y' off, but one of the neutrals in panel 'y' is still hot and have 120V.
curt swartz
Electrical Contractor - San Jose, CA
- Location
- San Jose, CA
- Occupation
- Electrical Contractor
Is there only a single raceway between Panel A and Panel B or are there multiple raceways with parallel conductors?
parallel raceway/conductors
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
I am always amazed at how much stuff "I remember wrong".:grin::roll:
curt swartz
Electrical Contractor - San Jose, CA
- Location
- San Jose, CA
- Occupation
- Electrical Contractor
If you only installed a neutral in one of the raceways between A and B you would not comply with 310.4(C)
this might be a voilation (I'm not sure), but this neutral is not part of the parallel conductors to panel B!! My understanding of intent of Parallel conductors is to have to same impedence (conductors have to be same number & length), and the additional neutral will not affect the current balance in both parallel runs.
What if we install 1 #2 AWG (for panel C neutral) in each conduit from A to B, and join them together in Panel B, and run (1) #2 (panel C neutral)from B to C.
kwired
Electron manager
- Location
- NE Nebraska
215.2(A)(1) requires minimum size of grounded conductor in a feeder circuit to be sized to 250.122.
For the 800 amp feeder that means a minimum size of 1/0 copper. After panel "B" it can be reduced to as small as 8 AWG if there is no more load than 8 AWG will carry.
You want your grounded conductor to be able to carry any faults imposed on it without compromising the conductor just like you would with an equipment grounding conductor.
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It is a violation of 310.4(B) [2008]. Each conductor must be paralleled.
However, the grounded conductor is not subject to 250.122(F), so you do not have to run a 1/0 in each conduit. Yet the Code does not provide a designated method for splitting a grounded conductor's size into two equivalent-ampacity conductors (i.e. 250.122 specifies size based on ocpd rating, not ampacity). If we use 110.14(C) 75?C termination temperature limitations as the basis, you would have to run two #4 at a minimum... so two #2 should suffice.
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Except you can not run parallel conductors unless they are 1/0 or larger. 310.4(A)
I don't see an issue with NOT landing the neutral in panel "B" but you are stuck as far as being code compliant, you say #2 AWG is the largest conductor you are allowed in each conduit without over filling and 1/0 AWG is the smallest you can parallel. I think it is time to actually look at the size of the wire (cross sectional mils.) and do the math to see is you can get away with it, possibly use a compact conductor to get a little extra out of it. Good luck. OR since the inspector only wants the neutral landed in panel "B" and he obviously isn't a member here, Well Ya might get away with a little, uh, HACK work :roll: (I am just kidding, do it right or don't do it at all)
I think that would work. Thanks!!!
kwired
Electron manager
- Location
- NE Nebraska
The neutral between A and B is carrying unbalanced current from a breaker in panel B (the one that feeds panel C) it is part of the feeder circuit. A neutral bus does not necessarily need to be installed in panel B. I would use Polaris or other similar connectors unless you see the need for future neutral loads from panel B
A possibility if you have metal raceways is to use the raceway as the equipment ground and the old grounding conductor for the neutral. There have been threads on this with a lot of debate over whether or not this would be a good idea. Only you can see the condition of the raceways and have an idea of whether or not they are electrically continuous (which they are supposed to be anyway), and decide if this is a good idea.
Yes. You're right. And I like your idea about the grounding conductor, but we do not have a grounding conductor, they're already using the conduit for that.
The distance between A & B approx 600ft, 3" Metal Codnuit -(3) #600 MCM, with no grounding conductor. The load in panel C approx 45Amps, and it looks like we can add up to 250 MCM, but I do not think that they can pull it all the way thru becuase of age of feeder. we do not care about future capacity at this point, next guy who comes in, or the next project they do, will have to replace this feeder.
It seems that a #2 in both conduit is the most correct approach at this point.
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