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Don Murray
 
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Default single phase from 3-ph



Chief McGee wrote:

This was mentioned a few days ago but would someone please clarify it for
me.
I am installing 3-ph to the shop. It is 200A delta wound, 2
transformers on pole, 3 hot wires 1 neutral from pole, ground rod driven
into the dirt and hooked to the neutral buss bar. Drawing with the meter
box shows the neutral wire coming from the middle of one side of the
triangle that forms the delta. Is this what is called "center tapped"?
I think I want to run 5 wires to each machine. 3 hots, 1 neutral, and
one ground from the machine base all the way back to the neutral buss bar in
the sub panel. Is this right?
I also want to have a 120 outlet and 120 work light on each machine. AT
THE MACHINE, I am going to pick one of the hot legs(NOT the power/stinger
leg) and the neutral. Will connect the ground leg in the light to the base
of the machine. Is this right or do I have to go all the way to the sub
panel with the wires?
Next, I have a 5-hp 220V single phase air compressor. For that I
think I need only 4 wires. 2 hots(NOT the power leg) 1 neutral, and one
ground from chassis all the way back to the neutral buss bar in the sub
panel. Is this correct?
I want this to be safe and legal. Thanks for your time, Chief.


Chief,

What you have is an open delta. You can have a look at a wiring diagram
of the bank of transformers at

http://murrayranch.com/Electricity.htm

Take a look at the diagram that is open wye-open delta. Don't concern
yourself with the primary or open wye. But the secondary open delta is
just what you have.

I can't answer your question as to the number of wires to each machine
as I don't know the inside code, my field is as a
lineman/troubleshooter.

Hope this helps,
Don