Farm Three Phase

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I'm with Wayne. 480 corner grounded. That will reduce the cost of panels and feeders since you don't have to bring the 4th wire.
 
Strathead said:
I'm with Wayne. 480 corner grounded. That will reduce the cost of panels and feeders since you don't have to bring the 4th wire.
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The OP said 480/240 3Ph 4W Center Tapped delta not 480V 3PH 3W corner delta, so the service needs 4W.

In any case you never need to run a feeder neutral unless the load requires it.
 
wwhitney said:
How's that?

With a 480V corner grounded delta, you only have 2 ungrounded conductors and could conceivably use panels with just 2 buses. But both 480/240V delta and 480Y/277 have 3 ungrounded conductors required to get 480V delta 3-wire to supply the motors.

Cheers, Wayne
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thanks...I read that incorrectly and you are 100% correct.
 
augie47 said:
I was curious having never seen such animal......:)

View attachment 2564349
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Yeah, it's an oddball for sure. I have heard of it, but never seen it in the wild. I don't see the point, because sure, you get 240V single phase, but no 120V, so you STILL need another transformer for that. So what have you really saved?

480/277V for sure. If anything ever has VFDs on it in the future, you do NOT want a Delta service of any sort.
 
ptonsparky said:
Absolutely not a corner ground! Not a fan, nope, no way.
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Especially on a farm where there tends to be non qualified working on things after initial install. 277 to ground is bad enough but 480 to ground is even worse. High leg isn't much better as it is 416 to ground. But we do have quite a few of those around here for more limited loads and they are supplied via open delta banks.
 
jim dungar said:
The OP said 480/240 3Ph 4W Center Tapped delta not 480V 3PH 3W corner delta, so the service needs 4W.

In any case you never need to run a feeder neutral unless the load requires it.
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jim dungar said:
The OP said 480/240 3Ph 4W Center Tapped delta not 480V 3PH 3W corner delta, so the service needs 4W.

In any case you never need to run a feeder neutral unless the load requires it.
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First, off I misspoke. You do have to run the neutral at the service, if it exists, but since I can't find the code right now, I think that may just be for a 4 wire wye service. Either way, the OP didn't appear to be saying he needed the center tap. So my post was to suggest that he not have a center tap provided.
 
The requirement is that the grounded conductor be run to the service, even if no loads use that conductor. The reason is that at the service you have the necessary bonding to the grounding electrodes and the EGCs.

You need to have a fault current path back to the source.

This applies to wye and high leg delta services. It would even apply to corner grounded delta, if you wanted to be really obtuse :)

Jon
 
Strathead said:
First, off I misspoke. You do have to run the neutral at the service, if it exists, but since I can't find the code right now, I think that may just be for a 4 wire wye service. Either way, the OP didn't appear to be saying he needed the center tap. So my post was to suggest that he not have a center tap provided.
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You must run the "grounded conductor" to the service disconnect or first for any voltage system whether it is a neutral conductor or not.

Beyond the service disconnect you must run an equipment grounding conductor and not bond to the "grounded conductor". Corner grounded systems tend to throw people off, even those that are in the electrical trades. That grounded conductor is a current carrying conductor, misunderstandings resulting in downstream bonds can lead to that current following unintended pathways, and on top of that the voltage to ground is the full 480 volts, so things you maybe doing wrong with on 120/240 volts and seem to get away with are four times the volts to ground when you do them on a 480 corner grounded system.
 
In my view and in this day and age, I would not even consider anything but a 480/277 grounded Y service for the various reasons already expressed.
 
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