rta53
Lifetime Supporting Member
We go a call from a customer this past weekend saying a pump was down on their water system. The service technician found that the feeder breaker had tripped. He reset the breaker but it tripped again the next day. The pump is a Grundfos submersible type although it is mounted on a frame and is not submersed in water. It is 17.5 HP 3-phase 480VAC. The FLA is 42. The running amps on each phase is around 33. When he checked the starting current 2 of the phases was around 77 amps but one was 95. The pump has been in operation for 4 years with no problems. One thing the tech told me was that the feeder breaker is 80 Amps. According to the NEC this could be sized at 100 Amps. I was expecting to see a difference in the running current but there was none. Could the higher starting current in one of the phases indicate a pump motor problem or is this normal? I am considering just replacing the 80 Amp breaker with a 100 Amp since this is what it should have been in the first place. What do you think?