Interesting one today, found a VFD for a Cond fan off on OL, overload. The fan itself ohmed out just fine. But in the spirit of digging deeper, I megged the wires from the vfd to the motor to ground. The Supco IDVM-550 is not a dedicated megger but it spit back 11 megohms. The wiring was replaced and all was good! Once I fished out the old wiring, I found some discolouration, a potential insulation weak spot. Megohm tests aren't just for motors/compressors but point A to B wiring as well. #teachme

Posted by HVAC Know It All at 2021-12-14 20:29:54 UTC