2 Heaters on Dual Pole GFCI Breaker


Old 06-22-15, 04:59 PM
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2 Heaters on Dual Pole GFCI Breaker

Hey all,

I have a 12-3 line MWC running out of my sub panel.
If I have two outdoor heaters at 120v rated at 1500w (12.5 amps) each, can I run each on one leg of the 20 dual pole GFCI Breaker?

Will each leg provide 20 Amps so that the CB will not trip, or is it a combined 20amps?

If not, any suggestions on how to wire without swapping out the 12-3 line (UF fed underground)?
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Old 06-22-15, 05:56 PM
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Each 120 circuit is 20 amps.
Old 06-22-15, 06:23 PM
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That sounds like good news!

To play devils advocate though....Will the potential 25 amps(12.5 +12.5) on the shared neutral to the GFCI breaker not trip the breaker? At that point does that mean the breaker is actually allowing up to 40 amps to pass through it before tripping?
Old 06-22-15, 06:39 PM
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When you run a circuit like that..... the loads technically get connected between the red and black wire so that the neutral only carries the imbalance.

There will never be more than a 20A load on the neutral wire.

Since you are running identical loads..... there will be 0A on the neutral if both heaters are running. If only one heater is running there will be 12.5A on the neutral.

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The blue squares are the heaters.
Old 06-22-15, 08:12 PM
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Thanks so much for the diagram, it jogged my memory, I am SOLD!

Apparently 1 year ago me knew what I was doing, and now, for some reason when I'm about to put in the heaters I was doubting myself.

Thanks again.

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