I have a pool pump that was throwing the breaker after a few seconds. Thinking it was a short somewhere I began investigating and thought it was the wire connecting to the pump. I replaced that section of wire. Now it will not throw the breaker, but the pump will hum after about 2 minutes for around 5 seconds and then stop and then hum again about 2 minutes later. The pump does not shut off though during the hum. The hum can also be heard in the circuit breaker. I am guessing every time the pump hums the circuit breaker hums (but not throw) at the panel. I took some reading at the panel and I am getting 120v out of each side of the breaker and then when I hear the humming the voltage seems to drop on one side to about 115v and then increases on the other side to 124v. When disconnecting the pump altogether I do not get any hum at the breaker (I did not measure voltage on each side when disconnected so I don't know if there is still some fluctuation). This certainly screams a bad pump to me, but I am hoping it is a bad breaker. Any assistance out there is appreciated.