Neutral connected to load but not upstream distribution panels

[mull982]

What would happen hypothetically if a 480-208/120 transformer fed a 208V three phase panelboard but there were only 3W+G ran between the transformer secondary and the panel and therefore there is no neutral pulled to panel. The transformer secondary wye point is solidly grounded at the transformer.

Now lets say out of the panel there is a branch circuit which feeds a single phase 120V load. The hot wire is ran through the branch breaker to the load as normal however the neutal wire from the load is ran straight back to the neutral or wye point of the transformer since there was no neutral pulled to the panel.

Other than the obvious code violations is there anything strange that would occur within panel feeder circuit or branch circuit from this arrangement (ignoring any ground fault detection that may be present). From what I can tell the load will operate fine as will the rest of the circuit and the only issues are related to code violations?

 

[augie47]

In a "real world" application, all would be fine.

 

[infinity]

If you connect the neutral to a bus in the panel (providing there is a neutral conductor to the X0) or directly to the X0 at the transformer the load would operate normally.

 

[mull982]

If you connect the neutral to a bus in the panel (providing there is a neutral conductor to the X0) or directly to the X0 at the transformer the load would operate normally.

Thats what I thougt.

Do you agree that this would be a code violation? Do you know which article specifically it would violate?

 

[charlie b]

I don't see how you could physically install what you describe without violating 300.3(B).

 

[kingpb]

If you can get a neutral back to the transformer, then why not just pull a neutral to the panelboard and make it a 3p, 4w?

 

[Joethemechanic]

I don't see how you could physically install what you describe without violating 300.3(B).

Maybe he is working on a K&T panel someplace that is not under the NEC

 

[templdl]

Isn't the neutral considered a current carrying conductor? A such wouldn't it be requiered to be run with the other phase conductors as it can't be run separately which ?
As CharlieB stated a reference to a possible Art 300.3(B) violation:
3) Conductors of the Same Circuit. All conductors of
the same circuit and, where used, the grounded conductor
and all equipment grounding conductors and bonding conductors
shall be contained within the same raceway, auxiliary
gutter, cable tray, cablebus assembly, trench, cable, or
cord, unless otherwise permitted in accordance with
300.3(B)(1) through (4).

Or have I misinterpreted the intent of the OP?

 

[mull982]

If you can get a neutral back to the transformer, then why not just pull a neutral to the panelboard and make it a 3p, 4w?

This is not an actual situation I'm faced with but rather just a hypothetical situation I was curious about.

Thanks for the replies.

 

[texie]

I agree with the others, it would work but would be in violation of 300.3(B). If it was a MWBC it would also violate 210.4(A). The OP raises an interesting question. I think we all assume that a feeder or branch circuit must have the ungrounded conductor connected to the same panel in all cases, but I don't see where the NEC specifically spells that out. Maybe a code proposal? I have seen this happen in the real world with side by side panels and I think it is a real hazard.