mxslick
Haven't seen one in years! But 3w 240 is fine.
Then you would be 'sharing' a neutral.
Your missing the point Don and I made, you share neutrals back to the source as soon as you reach the panel. The panel is not the source of the power.
There is nothing special in a panel to stop a hum.
Amplifiers can cause added harmonics on a shared neutral but that is a separate issue and not one that will cause a hum.
I would be looking for improper grounding and improper neutral to grounding connections.
tdhorne
It ties right into a sore subject. Anyone that cannot work safely with a multi wire branch circuit has no business doing electrical work.
I sure agree with you there.
Bob