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Old December 6th, 2002, 02:12 PM   #1
United States

drewcrew6 is offline
Join Date: Apr 2002
Location: allentown, Pa
Posts: 418
grounding power sources

Since we did 24vdc on this lets continue. What about a control panel with a transformer supplying 120vac (actaully any ac voltage) should 1 terminal be grounded?

I believe that you should. But have seen a decent amount of panels built with this spec'd to not be grounded. I have never been able to come up with a reason for this other than if a wire gets grounded for some reason (wear or cut into). Then the piece of equipment will continue to run with blowing a fuse or breaker. That would benefiet a continuos operation that has considerable down time due to control power loss.

But what if one of those wires come in contact with say a 480 vac line then the potetial of the 120vac is now up at possibly 480+120. Depending on the phasing that could be well over 600 volts the limit of most control wiring.

Sounds like a saftey risk .

Not to mention that the person servicing this knows its 120vac. And works with a little less care than if it was a 480vac potential which we all do but shouldn't.

Any comments gladly accepted

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