I am having a problem with an air conditioner circuit. When it starts up, the conductors in EMT are making a buzz for a split second and this is a concern to the homeowner. I think it has to do with the initial surge of current (117 LRA) in the metal conduit. How can this buzz be eliminated?
I think that it is not the metal conduit itself that is causing the problem but the magnetic forces between the individual conductors inside the conduit.
The current is making the wires attract or repel each other strongly at a 120Hz rate, and they are then probably vibrating against the walls of the conduit.
If you tightly twisted the wires before pulling them it might help. Or fill the conduit with some sort of goop.
As a practical matter, the two alternatives that come to mind are:
1. larger sized and therefore more rigid wires.
2. A soft start device as mentioned earlier.