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Our new microwave trips the AFCI almost every time we use it. Electrician says it is drawing too much power and we should return it.

Samsung over range Microwave 120 volts 1.5 kw AFGI 20 amp

Alaska Man
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nordy
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  • What make and model are your breakers and panel? – ThreePhaseEel Mar 28 '21 at 15:23
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    1,500 watts is 10 amps at 120v. so no way it's drawing "too much power", far more likely to trip because the AFCI is "thinking" there is an arc fault due to how the microwave is using power. Can you plug it into a regular outlet? If it doesn't trip the breaker then, you know it's a AFCI arc issue. Check all your connections, to the micro, including the outlet, eliminate any back-stab outlets by using the screws to attach the wires and see if that helps. If not, it's code legal to replace an AFCI breaker with a normal one to avoid nuisance trips. – George Anderson Mar 28 '21 at 15:48
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    Here are some other questions that may help you: https://diy.stackexchange.com/questions/215982/bosch-drawer-microwave-causes-arc-faults https://diy.stackexchange.com/questions/61663/why-does-my-microwave-trip-my-afci-only-when-its-mostly-empty – Jeff Wheeler Mar 28 '21 at 16:54
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    When the breaker trips, *what else* loses power? List every load on that circuit that isn't turned off. How many outlets are involved? – Harper - Reinstate Monica Mar 28 '21 at 17:29

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Your electrician is way wrong a 1.5Kw device only draws 12.5 amp a 20a breaker won’t trip below 2400w for current (usually beyond that for current based on an inverse time ratio). Microwaves convert the power to RF the wave shaping creates harmonics that the AFCI can not tell what they are. The AFCI thinks they are arcs and trips.

This tripping gets more common with larger microwaves and heavily loaded lighting circuits with electronic ballasts/drivers, and motor controls like for washing machines.

Electronic circuits have this issue and in some cases changing brands of AFCI device if possible may help.

In my state I the option I have with a dedicated circuit I can omit these devices in cases like these where the device is known to cause nuisance tripping so it would be worth checking your local code amendments.

Ed Beal
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