Just finished wiring the 120v side of my 'Kal-esque' enclosure, and powered it up for the first time.
I have 4 DPST contactors in the box (one as the main shut-off to the box, the other 3 controlling outlets for heating elements)
I have powered up each contractor, and one is a lot noisier than the others. Is it normal for the same model of contactor to have varying levels of 'hum'? Or may this be some indication of mechanical flaw?