Two panelboards of one

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George Stolz

George Stolz

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Let's say I have two 42 circuit panelboards, nippled together, called "1CL1" together.

Can I put circuits (1CL1 - 8, 10, 70) on the same neutral?
 
sharing neutrals

sharing neutrals

if your going to share neutrals outside of the normal network style (2,4,6)
(1,3,5) ect.. Make sure you know that your circuits are all different phases. I wired a cancer center in GA. last year where the engineer had no pattern to his circuit layout and we had to share neutrals that way.
 
George,

Do you have a choice, is there another neutral somewhere you can use??

Just giving you a hard time. The problem I see is, where do you land the

neutral, panel one or panel two, do you just run circuit 70 with no neutral

over to panel one and then out with the other circuits? Although it is not

very far circuit 70 will have no partner to cancel out flux. JMO
 
George,
Unless you run the hot for circuit 70 in the same nipple as the neutral for the second panel, you have a violation of 300.3(B).
Don
 
georgestolz said:
Let's say I have two 42 circuit panelboards, nippled together, called "1CL1" together.

Can I put circuits (1CL1 - 8, 10, 70) on the same neutral?
Click to expand...

What are U going to label the second panel of circuits 8,10, 12?

I'd Say no, ask for a claification to allow each panel to be lableled
"1CL1-A" and "1CL1-B".
or
But I have seen the higher number used in the second can, I think its a typo on that drawing (& who said theres a drawing) ...
 
I also agree this could lead to some problems with 300.3(B). Depending on how the designer of circuits has these two panels thought out (or not thought out), there could be a lot of conductors (neutrals) that would be a unnecessary waste of copper.

Of course I have to ask...why are you pulling ckt # 70 with the other 2 ckt conductors as opposed to pulling ckt # 12?
 
Ckt #70 would be on the B phase, same as ckt #10 & would require a separate neutral. Sorry George, I had to do that. Ckt #72 would be C phase & the way I look at your set up is, you have 2 separate remote panels, no matter how they are labeled. So, if you took a separate neutral for #72 to comlpy with 210.4(A) & 300.3(B) & met ckts 8 & 10 in a j-box, could you then connect all neuts together? As you would have 3 phases & 1 neutral.
 
I would throw a flag on that play, George. You have two panelboards, not one. Giving them collectively a single name does not make them one panelboard. Neither does physically connecting them with a short nipple.

210.4(A) says that all conductors of a MWBC must come from the same panelboard. You are suggesting taking some conductors from one panel and others from another panel. I call that a violation.

I know I am disagreeing with several members who have posted their opinions. I concede that I have not designed a system in which this question would have arisen, so I have never had to discuss it with an AHJ. But that is the way I see it.

I actually think that this is the specific question you were trying to ask. Am I right about that?
 
charlie b said:
I would throw a flag on that play, George. You have two panelboards, not one. Giving them collectively a single name does not make them one panelboard. Neither does physically connecting them with a short nipple.
Click to expand...

I agree with Charlie B, also if it were a truly a single panel it would be in excess of 42 circuits. Either way no go under the 2005 or earlier NEC.
 
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Thanks for the support Jim. But I should advise you (and the membership) that I have some reservations about my stated opinion.

Read the first sentence of 408.35 carefully. Note in particular the words, ?. . . of a . . . panelboard. . . .? The 42 circuit limit is for a single box. The words do not explicitly speak of 42 circuits as being the limit for a single panelboard. Does anyone interpret this sentence as saying you can have two boxes side by side, each with 42 overcurrent devices, and call this thing a ?84 circuit panelboard? (singular)? That is not my interpretation, but it is an interpretation that might be reasonably supported.
 
...Of a panelboard... I interpet as a single panelboard.
The code makes it clear when they mean more than one.

besides IMHO, The 42 rule is pointless and on it way out.
 
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The NEC definition of a panelboard allows for a "group of panel units designed for assembly in the form of a single panel...".

But, if an 84 circuit panel has two separate back boxes and two separate trims has it really been designed in the "form of a single panel"?
 
Thanks, Jim, for pointing me to the definitions. You just sealed the deal. Sorry George, but your hypothetical configuration is a violation.

Take a look at the few words, in the definition of ?panelboard,? that follow the first semicolon. You will note that a ?panelboard? is defined as (a bunch of stuff) ?designed to be placed in a cabinet or cutout box. . . .? Not two boxes; ?a box? (as in ONE box). So if you have to cabinets or two cutout boxes, you have two panels.

Please note that the phrase ?cabinet or cutout box? also appears in 408.35.

QED
 
charlie b said:
Thanks for the support Jim. But I should advise you (and the membership) that I have some reservations about my stated opinion.

Read the first sentence of 408.35 carefully. Note in particular the words, ?. . . of a . . . panelboard. . . .? The 42 circuit limit is for a single box. The words do not explicitly speak of 42 circuits as being the limit for a single panelboard. Does anyone interpret this sentence as saying you can have two boxes side by side, each with 42 overcurrent devices, and call this thing a ?84 circuit panelboard? (singular)? That is not my interpretation, but it is an interpretation that might be reasonably supported.
Click to expand...

I've seen "hundreds of circuits" panelboards in many stage lighting patchboards. But they tend to NOT be wired as MWBCs.
 
That was my suspicion as well, but I thought I'd recalled Roger having a different opinion at some point, on a different but related topic. I can't remember the context though.

Thanks for all the replies. :cool:
 
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