neutral

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rmonroe

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We have a three-phase wye system feeding our plant (480V 277V).
There is one busway in our plant that is a three-wire system (there is no neutral feeding this bus). I recently discovered that there is a lighting panel supplied from this busway that has no neutral. Would it be feasible to run a separate neutral from our main distribution panel, which is approximately 350 ft. from this lighting panel, in conduit and sized for this lighting panel. The lighting panel in question is now using Ground in place of the neutral.

thanks
 
Re: neutral

No that would also be a violation.

300.3(B) 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).
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You will have to run a new feeder from a source with a neutral for this lighting panel.

Or install a transformer to create a neutral.

Is the lighting connected to this panel HIDs?

If so you might be able to run the lighting at 480.
 
Re: neutral

I wish I could post a schematic because it would be (in my opinion) so much clearer, that the question would not have even come up.
 
Re: neutral

In order to correct this problem would I be ahead to purchase a transformer and size it for this existing lighting panel. The transformer would be three-phase 480-volt delta primary and three-phase 480-volt wye secondary.

Thanks
 
Re: neutral

Originally posted by rmonroe:
In order to correct this problem would I be ahead to purchase a transformer and size it for this existing lighting panel. The transformer would be three-phase 480-volt delta primary and three-phase 480-volt wye secondary.

Thanks
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i don't think anyone here can answer that question for you since no one here knows what it would cost you to run new wires versus installing a xfmr.

It occurs to me that there might be another out here.

If someone had run an insulated EGC out with the phase wires. maybe you could convert that to the neutral (if its large enough) and use the conduit as the EGC.

You would have to accept using white tape to mark the green wire as a neutral rather than an EGC, something that is a bit dubious, but its less dubious than what you have now.
 
Re: neutral

Bob,

The transformer would set just above the lighting panel. I would use the existing feed that is powering up my lighting panel now to feed the primary side of the transformer (480-Volt three-phase delta). Off the 480-Volt three-phase wye secondary side of the transformer I would now feed the lighting panel. This would give me my true neutral that my lighting panel needs for the 277-Volt.

If I was to run a new 100 amp feed to this lighting panel with the true three-phase wye system the cost would be must higher. The run would be approximately 350ft to 400ft to the questionable lighting panel. The cost of the transformer is $1,500.00 plus and minimal labor time compared to running a new feed.

Does this get you a better picture of what I?m trying to accomplish?

Greatly appreciate all the input.

rmonroe
 
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