It is quite rare for capacitor banks to hum. Much more likely that you're hearing the magnetics (transformers), which indeed have reason to be where they are. Good luck.
Thanks. Indeed those are transformers, upon further digging(for some reason, I think of transformers as big, these are not big but boy they emit this low-buzz sound). And indeed it has been very challenging to have them moved, because as you said they probably picked this location based on a reason.