Microwave and circuit breaker tripping

[Sibley]

I was using the microwave and it suddenly stopped. I checked, and a breaker had flipped. Reset the breaker, crossed my fingers.

Roommate used the microwave, it stopped. She unplugged it and plugged it back in and it worked for a little bit but then stopped. (She knows nothing about electrical stuff. I know a bit more.)

Microwave is 2ish years old. Nothing big is running. This has never happened before today. No known changes.

Next steps to diagnose problem? What info do you guys need?

[Dave1442397]

Do you know if there are any other outlets connected to that breaker? Have you added any new appliances lately, or had anyone use a hairdryer while the microwave was running?

Whoever wired our house must have asked their kitten to run the wires, because there is no logic to it at all. I ended up having a dedicated circuit put in for our microwave.

[Sibley]

I don't have a map of the circuits. We haven't had any problems before, and we've been here 2.5 years.

The gas oven was on, a few lights (3?), various appliances/electronics plugged in. My roommate's space heater is unplugged, and that's the only new thing in the past year or so. No hairdryers. Printer is off.

Could the breaker itself have gone bad?

[Sibley]

It's counter top. I'll move it and see what happens. There's plug in the dining room I know a different circuit.

I believe it's a 15 amp. No test/reset at the outlet, and I don't think there was one on the breaker.

[paddedhat]

Bender is on the right path, test it on another circuit to isolate the issue. Unfortunately, breakers fail a lot more often than most folks imagine, or maybe it's anecdotal, since I have changed many for reasons like this. It seems obvious to most of us with a bit of common sense, but don't let anybody "cure" the problem by continually resetting the breaker, after it trips. Residential breakers are cheap, and generally pretty effective at their job, but they can only handle a limited number of overload events until they can fail. It might just fail safe, and just quit, or it might blow up in your hand, if it's damaged internally.  Having experienced the latter, I can't recommend it. The other possibility is a weak connection at the cord/plug or a loose wire at the receptacle. Both issues will generate a lot of heat and draw excess current, causing a breaker trip. When it's operating, grab the plug and gently rock it back and forth. This may trip the breaker, or result in rather unsettling "crackling" noises. Check the prongs of the plug for scorching or burn marks. With the microwave turned off, unplug it. Does it feel normal, and take a firm grip to remove the plug, or is it loose and wobbly?

[Sibley]

Well, no obvious problems with the outlet, plug, etc. Will have to move the microwave and test it. I really hope it's the microwave. I've got a spare in the basement (trash picked), and I don't want to have to deal with the out of state landlord. Too much hassle.

[BudgetSlasher]

It's counter top. I'll move it and see what happens. There's plug in the dining room I know a different circuit.

I believe it's a 15 amp. No test/reset at the outlet, and I don't think there was one on the breaker.

I believe that large/fixed appliances (such as built in microwave) are supposed to have their own circuit, however a counter microwave is most likely not on a dedicated circuit. If you move it to a clearly different circuit (you'll need to map the microwave circuit or just find an outlet that still works when the microwave circuit is off) and that breaker trips it is the microwave. If it doesn't trip, I would recommend mapping the circuit (especially if you are uncomfortable replacing the breaker yourself); you might find that there is something else on the circuit that in combination with the microwave overloads the circuit (it is winter, perhaps there is a small heater or even a relocated light to deal with the dark days). I've found that circuits can have an odd assortment of things connected to them, I have one that feeds the pantry light, the GFI outlet on the kitchen island, the water softener in the basement, and the outlets in the garage including the ones that feed the door openers.

Do you know the wattage of the microwave? That might give a clue as to how likely another item on the circuit is to trip it.

[Sibley]

Well, moved the microwave and have used it a few times. So far so good. We'll keep it there for a while, see if it has problems.

1000 watts. Google lcs1114sb and it'll come up.

We've lived here for a few years now and have never tripped a breaker. It's a rental - if the breaker (or outlet) is bad, we'll contact the landlord.