It is a bad element(s).Check both units, and replace the bad ones. bad thermostats would pop out the red reset button. Bad elements will trip the breaker and/or the reset button. Also check the wiring in the box on the top of the heater and in the main panel for loose connections or melting aluminum wire.: All of a sudden, my water heater has been tripping the circuit breaker. It doesnt seem to do it all the time. If I reset the breaker, I can hear the water heater start to run again. Does this sound like a : bad heater element, thermostat, or both ? I reset the : top thermsostats reset button, but that didnt seem to make any difference. Please help !!