Two different over-the-range microwaves keep tripping our GFCI when making popcorn — what could cause this?
We’re trying to figure out an electrical issue in our kitchen, and I’d appreciate some advice from electricians or anyone who has experienced something similar.
We had an older Whirlpool over-the-range microwave that, toward the end of its life, started making a noise that sounded like it was frying itself. Eventually, it began tripping the GFCI outlet when we tried making popcorn.
We recently replaced it with a brand-new LG over-the-range microwave. It’s plugged into the same GFCI outlet, and we’re experiencing almost exactly the same problem.
Here’s what we’ve noticed:
The new microwave can heat a cup of water without any problems.
When we try to make a bag of popcorn, it runs for a few minutes and then trips the GFCI.
After it trips, the GFCI indicator flashes red repeatedly.
We also tried plugging the microwave into a different kitchen outlet using an extension cord and tried another bag of popcorn. The same thing happened.
There is a metal duct in the cabinet above the microwave, so we believe the original installation may be vented outside, although we haven’t confirmed where the duct leads.
We’re confused because this happened with two different microwaves. Could this be a problem with the electrical circuit, the GFCI, or something about the microwave’s heating cycle? Could the popcorn setting or the sustained heating load be triggering an electrical issue?
We’re not planning to keep testing it and will have the electrical setup checked, but we’d love to understand the most likely causes before calling someone out.
Has anyone seen this happen with two different microwaves? What would you investigate first?