I have witnessed the same thing in two different situations. One was in a hotel electric room. The conduit feeding the elevator would literally make a "clink- clink" sound every time it operated. I amprobed the conductors and the amperage was going from 0 to almost 100 amps.
The other time was for a large pneumatic control system air compressor. The conduit was making more of a buzzing sound every time the compressor started.
My question is: Is this bad for the conductor insulation as the conductor moves around in the conduit?
