Circuit Breaker 'humming' noise
I wired in an electromechanical time clock for my electric hot water heater. The timer is a TORK Model 7102 SPST 40 amp switch. The timer switch clock runs on 240 volts. I've noticed that when the switch closes and energizes the water heater, the main panel box circuit breaker dedicated to the water heater makes a low, slight humming sound. The sound stops when the timer switch is off. The breaker is a 30 amp "pushmatic" style with 10/2 wire. The water heater element is 240 volts, 4500 watts. Is this humming sound normal or does it mean I have a defective circuit breaker or that I've wired something incorrectly??