3 Wire feeding 4 wire panel

[dtown8888]

In a sticky situation and I greatly appreciate your advice regarding a recent inspection at our warehouse. We have 200amps, 3 wire (no neutral) feeding a Siemens P2 Panel, 480/277V, 3 phase, 4 wire. Engineer signed off on the 3 Phase, 3 Wire panel and stated no neutral is required, per the equipment coming off the panel. However, the inspector stated since the label from Siemens panel states 480/277V 3 Phase, 4W, the feeder cable must have a neutral. The Siemens panel does have a neutral bus/plate on it.
Inspector said we need to replace the panel, rather the inside part of the panel, so we can keep the breakers, etc. After spending half the day on the phone with suppliers, I came to the realization there are no 480/277, 3 phase, 3 wire panels on the market and it would take over a month to custom order. This is the last 'change' until our system goes live. Please note, the feeder bucket is nearly 200 ft away and rewiring with bigger conduit will be a big project.
The inspector cited NEC 110.3 both (A) and (B), comply with listing and labeling at panel 3 phase 4 wire requires a neutral to be installed.
What options do we have?
Is the inspector wrong? Is engineer wrong?
I did contact Siemens and we are trying to get a letter sent from them to inspector stating a neutral is not required and panel can function as wired.
I appreciate any input you may have about this situation. I will try to attach pictures.

 

[augie47]

(I allowed this thread from a non electrician as the OP is simply asking a technical/opinion question)

 

[zbang]

(Without cracking the code book to check....)

You mention that this is fed from a "feeder bucket" so it isn't a service panel. Assuming that the source end is a properly bonded 480/277Y connection, I can't see why you would need to run a grounded(neutral) conductor if it's not needed for the utilization equipment. I think the inspector is, um, confused. OTOH, I'd punt this back to the engineer.

 

[dtown8888]

Thanks for the reply. It is properly installed and the cables are coming from service panel. The meter it is on is on a 200amp bucket. Not sure if I am speaking the language.
Basically I am trying to figure out if our current subpanel with the 4 wire siemens label can be used even if we have 3 wires coming in, minus neutral.
Appreciate the help

 

[templdl]

In a sticky situation and I greatly appreciate your advice regarding a recent inspection at our warehouse. We have 200amps, 3 wire (no neutral) feeding a Siemens P2 Panel, 480/277V, 3 phase, 4 wire. Engineer signed off on the 3 Phase, 3 Wire panel and stated no neutral is required, per the equipment coming off the panel. However, the inspector stated since the label from Siemens panel states 480/277V 3 Phase, 4W, the feeder cable must have a neutral. The Siemens panel does have a neutral bus/plate on it.
Inspector said we need to replace the panel, rather the inside part of the panel, so we can keep the breakers, etc. After spending half the day on the phone with suppliers, I came to the realization there are no 480/277, 3 phase, 3 wire panels on the market and it would take over a month to custom order. This is the last 'change' until our system goes live. Please note, the feeder bucket is nearly 200 ft away and rewiring with bigger conduit will be a big project.
The inspector cited NEC 110.3 both (A) and (B), comply with listing and labeling at panel 3 phase 4 wire requires a neutral to be installed.
What options do we have?
Is the inspector wrong? Is engineer wrong?
I did contact Siemens and we are trying to get a letter sent from them to inspector stating a neutral is not required and panel can function as wired.
I appreciate any input you may have about this situation. I will try to attach pictures.

Keep in mind that MCCs are often 3ph3w. W/ground because MCCs by in large only feed 3ph motor loaded. We hy ABb the additional expense of a neutral bar that is not used.
With your panel, you have the 480v L-L-L and should have a ground bar. Then the issue if that the panel should be labeled 480v 3ph3w w/gr w/o the 277v, the 277v implying that there is a neutral when there isn't a neutral assuming that it is a sub panel where the neutral would be insulated and isdolated from the enclosure and EGC. Wouldn't it be thern a matter of having an incorrect nameplate? This is they way that I see it. Comments?

 

[ActionDave]

With your panel, you have the 480v L-L-L and should have a ground bar. Then the issue if that the panel should be labeled 480v 3ph3w w/gr w/o the 277v, the 277v implying that there is a neutral when there isn't a neutral assuming that it is a sub panel where the neutral would be insulated and isdolated from the enclosure and EGC. Wouldn't it be thern a matter of having an incorrect nameplate? This is they way that I see it. Comments?

I disagree completely. 480/277V is the rating of the panel. It has nothing to do with the conductors brought to the panel.

 

[ActionDave]

Thanks for the reply. It is properly installed and the cables are coming from service panel. The meter it is on is on a 200amp bucket. Not sure if I am speaking the language.
Basically I am trying to figure out if our current subpanel with the 4 wire siemens label can be used even if we have 3 wires coming in, minus neutral.
Appreciate the help

If there are no line to neutral loads then a neutral is not required at a sub panel.

Three wires indicates three hots and metal conduit for an equipment grounding conductor with no line to neutral loads fed from the sub panel. Is this what you have? If it is you are up to code.

This is a fight your electrician should be having with the inspector, not you.

 

[templdl]

I disagree completely. 480/277V is the rating of the panel. It has nothing to do with the conductors brought to the panel.

Good point in that regard. If it is the rating of the devices, yes, with a 480y/277 system the OCPDs would be allowed to be rated 480/277.and not just 480v. My concern would be the lack of a neutral which may be somewhat confusing in that 480/277 would imply that there was a neutral available. But then again this wold be obvious to a "qualified person" and be as non ißue.

 

[kwired]

I disagree completely. 480/277V is the rating of the panel. It has nothing to do with the conductors brought to the panel.

I agree. What this means is the system supplying the panel must be 480/277, it can not be supplied from 480 delta, which would end up with more then 277 volts to ground on at least one line. The panel itself may be able to withstand more then 277 but only breakers made to fit it are rated 277 or 480/277 so sort of doesn't matter. (somewhat of a guess on the panel rating, based off what I know of other brands and what is probably a similar comonent)