Old 01-11-00, 09:47 AM
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When adding a 3phase subpanel to allow 3phase equipment to be operated out of this new panel, is four or five wires reqired. I know that I would need five wires if I was using eqipment that needed a neutral wire, but I'm not sure if I need the additional wire in this case.
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Old 01-11-00, 05:18 PM
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I not sure just what you plan on doing.
But if this is a subpanel, that is you could run other things later from this panel, and it is not an open delta type (has high leg of 220 volts) you can generate 120 volts from this panel. Consequently you would need a neutral.
However, you seem to speak in the singular. Panel for one piece of equipment. This is called a disconnect switch and is not a true panel at all, and if the equipment does not need a neutral, then you do not need to run a neutral to the disconnect switch for the piece of equipment. The fifth wire you refer to I assume is the ground. If this is all metal conduit you don't need a ground either. The metal tubing is your ground provided you use proper fittings.
Also, you don't indicate if this will be a motor. If so, you actually need a combination switch/motor control to protect your motor.
I hope this helps you a little.
Old 01-11-00, 10:19 PM
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hi broth,
as david stated it all depends on whather it is a sub panel or a disconect. if is a sub panel id pull in the nutural for future use even though u dont need it now, as 2 your ground if u use metal conduit as david stated u dont need the ground in the conduit but i would still drive a ground rod and connect the panel ground bar not the nutural bar to it, also dont bond the ground bar and nutural bar together(ie connecting them together useing a piece of wire)
Old 01-12-00, 09:58 AM
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Thanks for the information. I didn't explain the situation very well in my original message. A new 100 A 3phase panel will be set, with the power coming from the main gear. The new panel will have two pieces of 3phase equipment connected to it. Their amperage will total 72 A, which will leave very little space for expansion. That's why I was wondering if I needed to bother pulling a neutral wire. I thought that the code may require it. I normally try to avoid using the conduit as a ground. Thanks again.

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