Originally Posted by Oaklevel
Are you running the water heater on electric as well ??? It draws a lot of AMPS also............
Assuming the question is to me ...
Yes although the heater should not have been on at the time the breakers were thrown. I suspect that it is as others have suggested - the combination of the AC compressor load and the microwave on high that just went over the 30A threshold.
Since that time we have had the lights on, the TV on, ran a Ninja blender and had other "normal" electrical loads and there was no problem. Microwave and AC are the only two that would cause this to happen.