Lighting, Light Fixtures, Ceiling and Exhaust Fans - Need a fix to Shoplight Harmonics

I have 5 shoplights that are plug ins all going to one Siemens 20A breaker. Nothing else is plugged to the breaker. I have another set of 6 shoplights set up the same way on a separate Siemens 20A breaker, again with nothing else on it.

I can turn on the lights, and the more that are turned on, an increasing hum comes from the breakers.

It has been diagnosed as a 60Hz hum. :wall:

How can I correct this? :confused:

The breakers hum because they don't know the words....just kidding. Are the shoplights on both circuits the same brand, type, etc.?? How old are these particular lights, and what type of ballasts do they have?? Were they all installed at the same time, or is it an older string you are having the problem with?? We can start there. Also, can you elaborate on how exactly these lights were diagnosed as a "60Hz hum", and what testing method was used to establish this. Post back, and we'll see what we can do for you.