Multiwire circuit question


Old 08-28-15, 04:26 PM
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Join Date: Aug 2015
Location: USA
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Multiwire circuit question

Is it legal to connect say the red and black (3 wire cable) to 120(different phases) and the white to neutral? Have been told the phases cancel each other out.
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Old 08-28-15, 04:39 PM
Join Date: Jan 2011
Location: USA
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Post makes no since.
The more details you can give the better.
What is it your really trying to wire up?
Old 08-28-15, 05:04 PM
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Location: Maryland
Posts: 14,587
What you are talking about is called a multi-wire branch circuit. Properly wired the neutral current is the difference of the hot current. A double pole or two handle tied breakers are needed.

As newer codes call for afci protection they are being used less.
Old 08-28-15, 08:14 PM
Join Date: Mar 2010
Location: USA
Posts: 3,093
Yes you may, and yes you must in this situation connect the red and black to different phases of a 3 phase system or opposite legs of a single phase 120/240 volt system when wiring up this kind of multiwire branch circuit..

However do not use the "high leg" in a 120/240 volt delta 3 phase system for this.

The high leg measures about 208 volts hot to neutral and is normally used only with 3 phase tools and appliances (used together with both of the other phases).

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