Common Neutral Question

[lpena]

HI, I have a customer saying that we have a code violation regarding a shared neutral connection. We have two panels: one panelboard (for power distrubution) and one control cabinet. (see attached) Basically, my customer is only supplying 120/240VAC to our panelboard. From the panel board we ran wires to our control cabinet to power the devices on this cabinet. The issue is that we only ran one neutral wire from the panelboard to the control cabinet. We connected this neutral wire to a stack of terminal blocks that are jumpered together. We connected all the neutral connections on the control cabinet to these terminal blocks. Is this a code violation? Customer is telling us that we need to run individual neutral wires from the control cabinet to the panelboard. In other words instead of just one neutral wire we need 12 (we have 12 branch circuits). Is the customer correct? To me it seems that they way we have it wire now is OK, but I just wanted to get some feedback from the forum. Thanks

 

[luckylerado]

HI, I have a customer saying that we have a code violation regarding a shared neutral connection. We have two panels: one panelboard (for power distrubution) and one control cabinet. (see attached) Basically, my customer is only supplying 120/240VAC to our panelboard. From the panel board we ran wires to our control cabinet to power the devices on this cabinet. The issue is that we only ran one neutral wire from the panelboard to the control cabinet. We connected this neutral wire to a stack of terminal blocks that are jumpered together. We connected all the neutral connections on the control cabinet to these terminal blocks. Is this a code violation? Customer is telling us that we need to run individual neutral wires from the control cabinet to the panelboard. In other words instead of just one neutral wire we need 12 (we have 12 branch circuits). Is the customer correct? To me it seems that they way we have it wire now is OK, but I just wanted to get some feedback from the forum. Thanks

You could get away with 6 neutrals and handle ties but either way you nay not use the neutral terminal block the way it is drawn.

Each circuit (12) needs a neutral or each MWBC (6) needs a neutral and handle tie. Assuming of course that your loads are 120V.

 

[augie47]

From what I can see you are in violation of 200.4
Installation.Neutral conductors shall not be used for more than one branch circuit, for more than one multiwire

branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere

in this Code

.

 

[jaggedben]

The only way I can maybe see it being okay under the code is if the PLC cabinet is a single listed assembly and its instructions very explicitly tell you to use in that way. I'm doubtful, though, that this will be the case. Those isolated neutral terminals that you jumped together would seem to suggest that the PLC box is intended to have multiple neutrals run to it.

One thing I'm unclear on is why there are breakers in both places.

 

[jap]

It seems odd that the control cabinet doesnt have (1) large feed coming from the panel, then, broke down into smaller circuit breakers for control if multiple circuits were needed.


JAP>