Seems Donna Ryan's answer is greyed out, partially for good reason. (Changing to higher power breakers that were not designed for the wiring is not safe and does cause a fire hazard.)
However, she has an EXCELLENT suggestion that I'd never have thought of. For those that have an old style stove that has an auxiliary outlet, using this "Aux outlet" MIGHT work in some instances. Here is where and when it will NOT work, or might cause other problems:
- If your stove is running 100% oven and burners, and then you try your microwave, it will likely throw the stove breaker. Otherwise, it will likely be OK.
- If your stove breakers are less than 20A + 20A = 40A, it will still likely throw the stove breakers, even though it is only using one of the 40A circuits, (You would be using only the 20A., since the stove gets the 40A from using two 20A breakers, two 110v out of phase circuits.)
- If your stove has it's own "fast" fuse that is rated at 10A, that fuse will likely blow. (Replacing that with a "slow fuse" of the same size as your RUNNING amperage and not your STARTING amperage would be safe and likely work.)
The key to the problem here was given by @GregMac when he said that the startup power was likely 2A, which can tip you over your 15A or 20A breaker. I'm now wondering that if in some microwaves, that 2A isn't a little bit low and draws more power than that.
@GregMac is a bit wrong about "running the microwave on low vs high power" though. I've replaced several magnetrons and so I'm familiar with the circuitry of most microwaves. Power is either applied to the "transformer / diode / capacitor" supply and the magnetron, or it is not. The "low" is provided by turning the magnetron on and off, usually some fraction of 30 or 60 seconds or so. This makes the problem WORSE, since the microwave is starting every time it cycles. In my instance, most of the time mine trips the breaker when in low, and not the first time it is started.
Personally, I will consider replacing the breaker and see if that helps, since I don't have anything else in my 20A circuit when it trips. Although it is possible that the transformer could have some shorted windings, it appears they are built like tanks and should last forever. (WARNING -- Do NOT replace the microwave's magnetron yourself, unless you KNOW what you are doing, since it can and DOES kill many that try, and they die WHEN IT IS UNPLUGGED!)
I think if there was some device made that would limit or eliminate the surge during start, most of this problem would be eliminated. If anyone knows of some method or device, I'd be interested in learning about it.
@Donna Ryan's answer might be removed at some point, (or even better, just EDIT that part and warn others to NOT replace with a larger breaker). So I thought I'd repeat WHY her suggestion likely works:
Donna --- Advise others to not "put a higher powered breaker" in, and then your answer is very good and VERY useful. (Steven and BMitch are right).
Why does your method work?? Your stove has it's own 220v DOUBLE circuit breaker with a (likely) much higher amperage rating to run itself. Even though you are only using one of the 110v sides, it is still isolated from other circuits, so if stove is not running it is VERY likely to work better that way, than your regular outlet.