AC Feeders

ThomasT2025 · 2026-03-30T07:45:03-0400

Hey Mike! I need to size a feeder for a subpanel for a couple AC condensers.

How would I size that? Would it be like sizing for motors?

Thanks!

Elect117 · 2026-03-30T13:23:26-0400

Mike is a sponsor of the forum but I don't think he participates.

And you would use article 220.

Easiest way is to calculate the kw with MCA and rated voltage. Add them up. Do your calculation to get the current and there you go. We would need the # of condensers and the nameplate data voltage, phase and MCA.

infinity · 2026-03-30T13:27:45-0400

Elect117 said:
And you would use article 220.

Easiest way is to calculate the kw with MCA and rated voltage. Add them up. Do your calculation to get the current and there you go. We would need the # of condensers and the nameplate data voltage, phase and MCA.

Why would you use the MCA for each unit? The MCA already has a 25% factor added to it for the largest load of each unit. Wouldn't you need to only use the 25% adder just once?

curt swartz · 2026-03-30T13:30:55-0400

infinity said:
Why would you use the MCA for each unit? The MCA already has a 25% factor added to it for the largest load of each unit. Wouldn't you need to only use the 25% adder just once?

Yep, use the MCA from the largest unit then add the individual motor loads of the other units.

Elect117 · 2026-03-30T13:33:03-0400

infinity said:
Why would you use the MCA for each unit? The MCA already has a 25% factor added to it for the largest load of each unit. Wouldn't you need to only use the 25% adder just once?

Ya. But I was just saying the easiest way. There are other ways to do it that would be code complaint.

AC Feeders

ThomasT2025

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Elect117

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infinity

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curt swartz

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Elect117

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