Irrigation pump 480v 3wire no equipment ground??

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As stated by others, treat it as a single phase service with one heck of a neutral load. Hopefully the wires were sized to compensate for VD at the time of installation. Might be a good time to meg those buried conductors to make sure they are good. An open or fault in the grounded phase will create a very noticable if not deadly situation at the load end.
 
Big Question about Grounding...

Big Question about Grounding...

I was reading up on the grounded conductor in this service in the '08 code and found this article which really throws everything posted here so far into question. Is this article applicable to my situation? Thanks for all the feedback...

Article 250.20 B(1)

States if the voltage of phase to ground exceeds 150v, to not ground? :-?
 
gmsoucy said:
I was reading up on the grounded conductor in this service in the '08 code and found this article which really throws everything posted here so far into question. Is this article applicable to my situation? Thanks for all the feedback...

Article 250.20 B(1)

States if the voltage of phase to ground exceeds 150v, to not ground? :-?
Click to expand...

Re-read that article, that's not what it says. I think you want 250.26(4) anyways.
 
It is not exactly what it says. It is the inverse, which is the way most of the code is written. I will read the article mentioned. Maybe you could explain what it says if what I am understanding is incorrect.:smile:
 
gmsoucy said:
It is not exactly what it says. It is the inverse, which is the way most of the code is written. I will read the article mentioned. Maybe you could explain what it says if what I am understanding is incorrect.:smile:
Click to expand...

Ok, in the sentence under 250.20(B) 2008 nec it says; "premises wiring systems SHALL be grounded under any of the following conditions"
"Shall" is a mandatory rule, so therefore it must be grounded. But I still think you should start with 250.26(4) to answer your op.
 
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Ok. I realize that is the situation. But does it not also mean that it is not required to be grounded, if the service doesn't fall into the "shall" category???
 
gmsoucy said:
Ok. I realize that is the situation. But does it not also mean that it is not required to be grounded, if the service doesn't fall into the "shall" category???
Click to expand...

Yes. In this case the service is not required to be grounded. It does not fit 250.20(B), in fact, look at the FPN on 250.20(A). It is permitted to be grounded. If it were ungrounded 250.21 woud require phase monitoring.

Ih has been my understanding that "ungrounded" systems are used primarily by processes where unscheduled shut down of equipment is costly or dangerous. The systems is monitored for "faults" that can be fixed on a scheduled basis.
I have been told the grounded delta system was incorporated to save money by allowing two pole (two fuse) disconnects rather than 3 pole.
I have no idea if thats a fact, but in a huge industrial complex, the savings would add up.
 
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