Panel Feed Wire Sizes


Old 01-18-05, 03:43 PM
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Join Date: Jan 2005
Location: United States
Posts: 455
Panel Feed Wire Sizes

If a Sub-Panel is 50 amp / 220 volt it should be served with #6 or #8 wires for the 2 hot leads and the common (depending on the distance from the main to the sub). The Ground should be #10 wire. I think that's correct.

As I understand it, this is the equivalent of 100 amps at 110 volts.

Now, here's my question. How can the Common which is the same size as each of the hot wires handle the current provided by both? IOW, why are not 2 equal size wires needed for the common?
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Old 01-18-05, 03:51 PM
Join Date: Jan 2002
Location: Chicago
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The two hots are out of phase. In another words, when one hits the peak the other is in the valey. For a perfectly balanced panel you would have no current flowing through the neutral, they would just cancel eachother out.
Old 01-18-05, 03:53 PM
Join Date: Sep 2000
Location: United States
Posts: 18,497
Depends on what it powers, but most of the time, #6 is going to be the right answer.

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