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Old 06-26-2011, 05:41 AM   #1
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MWBC (split 220V) -- code and good practices


Here is a follow-up question to my earlier barn wiring question. When using MWBC to provide two, 110V circuits, can the two hot wires (poles) be used to also provide power to a 220V device? This question is about both code and good practices.

My underlying concern is if one of the 110V circuits was running a motor, would the phase shift be enough to cause problems (like over heating) with the 220V device. That device in this case would also be a motor (1HP at 220V).

John
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Old 06-26-2011, 07:29 AM   #2
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MWBC (split 220V) -- code and good practices


Motor should be feed by it's own 240 volt circuit
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Old 06-26-2011, 11:13 AM   #3
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MWBC (split 220V) -- code and good practices


The motor alone requires #14 wire with a 20A breaker.
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Old 06-26-2011, 02:44 PM   #4
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MWBC (split 220V) -- code and good practices


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The motor alone requires #14 wire with a 20A breaker.
All wiring is 12 gauge and the breakers are 20A. The two poles for the MWBC would be ganged to work together.

When you say "alone" do you mean the motor must have its own circuit and breaker, or do you mean the minimum wiring to the motor (including the 110V circuits) is 14 gauge?

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Old 06-26-2011, 02:52 PM   #5
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MWBC (split 220V) -- code and good practices


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Originally Posted by john4153 View Post
All wiring is 12 gauge and the breakers are 20A. The two poles for the MWBC would be ganged to work together.

When you say "alone" do you mean the motor must have its own circuit and breaker, or do you mean the minimum wiring to the motor (including the 110V circuits) is 14 gauge?

John
Seperate circuit for the motor. #14 is compliant, but #12 is fine also.
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Old 06-26-2011, 03:26 PM   #6
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MWBC (split 220V) -- code and good practices


Thanks to you both. I drew it up this afternoon, and the motor will have a separate circuit.

John
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