i found a 277v b.c. coming from a building into a parking lot ground box that feeds part of the lighting, and another 277v b.c. coming from a building across the parking lot feeding other lighting... both in the same ground box. what code section does this violate, if it does? and what could be done to fix this? put a barrier in the box? identify each circuit with tags saying which building the power comes from?

Cindy,
I don't think that there is a code rule that would prevent this installation or require separation. Maybe you could stretch the definition of "structure" and call the junction box a "structure" and then 225.30 would limit you to one source, but if the box is a structure, then 225.31 would require a disconnect.
Don

Cindy

I will look to see if there is any 'code violation', I am not sure.

But in answering your question on what to do to fix it, I would at least tag the sets separately with a 'very permanent' method noting that they are fed from different buildings! Who knows what the potential difference between the 2 sets really is.
Even if this is not code, as has been mentioned many times before, code is the minimum necessary to pass an inspection.
Pierre