Surely seems odd but we do it all the time. On a three family dwelling with a 200 amp service I would put three 70 amp panels and one 30 amp landlord panel. This would allow you to draw 240 amps at full load. Will this ever happen? No. Does any one do load calculations for this. Nobody I know. My load calculation for this would be to ask the owner if the main on the existing service (usally 60 or 100 amp) ever blows or trips out.
