split circuit in two different loadcenters

Status
Not open for further replies.
M

-marty

Senior Member
Location
Alaska
Two loadcenters side by side. Panel A and panel B. Panel B is fed from panel A. 208/120 three phase.

Conduit enters into panel A and contains two black, two white and one green. One black and one white go through nipple between panel A and B. So that one black and one white terminate in each panel. No problem.

Now, same scenario as first paragraph except - 12-3 mc enters into panel A.

Question - Can black and white terminate in one panel (black phase) and red terminate (red phase) in panel b?

This just doesn't seem right so I've never done it but I always wondered if it was right or wrong.

I will gladly search the code for this answer if someone would direct me to the right section.

Thanks
 
No. All conductors [of multiwire branch circuits] shall originate from the same panelboard... 210.4(A)
 
macmikeman said:
Question, Is panel B actually a feed thru setup from lugs on panel A? Or is there a main breaker for panel B in panel A?
Click to expand...

I was thinking the same thing.

IMO it would be a smart move to consider them separate panelboards regardless of a feed through set up.
 
macmikeman said:
Question, Is panel B actually a feed thru setup from lugs on panel A? Or is there a main breaker for panel B in panel A?
Click to expand...

Does it make a difference? 100-I "Panelboard: A single panel or group of panel units, designed for assembly in the form of a single panel..." I believe the designed for assembly is referring to a manufacturer's design and subseuently labeled/listed/approved for and as such. The use of a feed-through nipple indicates two individual panelboards to me. Does simply sharing the feeder circuit and an abutted or close-by installation relinquish the requirement?

Granted, an assembly of panel units within one enclosure is electrically no different. Yet such a wiring method is permitted in this case.

PS: Don't kill the messenger...
 
Smart $ said:
The use of a feed-through nipple indicates two individual panelboards to me. Does simply sharing the feeder circuit and an abutted or close-by installation relinquish the requirement?
Click to expand...

We get 'double tub' feed through set ups that the supplier and engineers refer to as one panel board.

That said, if it was 'one panel board' than we would limit ourselves to 42 circuits total. ;)
 
I'd say that the 2 (or 3) wires of a MWBC should always be in the same panel and, even if not mandated, the breakers should be side-by-side to minimize the chance of overloading a shared neutral.
 
LarryFine said:
I'd say that the 2 (or 3) wires of a MWBC should always be in the same panel and, even if not mandated, the breakers should be side-by-side to minimize the chance of overloading a shared neutral.
Click to expand...
Larry wouldn`t the only time they would have to be side by side is so they could have a handle tie if landed on the same yoke,so that both ungrounded conductors could be opened together.
 
Not to say you couldn't handle-tie more circuits together for eccentricities' sake. No prohibition on having the two circuits several handles apart, and handle-tying all the unrelated neighbors in between, IMO.

Horrible design choice, but legal nonetheless, IMO... :)
 
I have actually seen a two section panelboard, 42 circuits in each section with only one neutral bar. All circuit neutrals from one panel terminated in the other. I think that I have a photo somewhere.:confused:
 
Bob,

You need to read all of 408.35. The limitation is on 42 circuits in "...any one cabinet or cut out box."

The 100 definition of panelboard is not very helpful, it says " A single panel or group of panel units.."
 
jim dungar said:
Bob,

You need to read all of 408.35. The limitation is on 42 circuits in "...any one cabinet or cut out box.""
Click to expand...

Jim, I am missing your point entirely.

We where talking about two enclosures.
 
Bob,
We get 'double tub' feed through set ups that the supplier and engineers refer to as one panel board.

That said, if it was 'one panel board' than we would limit ourselves to 42 circuits total.
Click to expand...
I think that Jim's point is that each tub is a cabinet or cutout box and that the 42 circuit limit in 408.35 applies individually to each "tub".
Don
 
short and sweet is not always understandable

short and sweet is not always understandable

Sorry Bob and thank you Don.

Yes the 42 circuit limit is per enclosure or cabinet not per panelboard. I am sure this has to do with limiting the amount of flammable/combustible cotton and rubber that might be in any one area.
 
Status
Not open for further replies.
Top