2" pipe size is good, just watch the gauge wire you are using. You want to reduce voltage drop as much as you can. Also no more than a total of 4 90 degree bends without a pull box. As a matter of economy aluminum is used for feeders. #2 Al is minimum for 100 amps and I would move up a size (#1) if over 100' per run. Total amperage use gets weird. In the past I wired a lot of 16 & 20 unit apartment buildings all with a 400 amp main. Electric stoves and window shakers for A/C. In theory each unit only could consume 20 amps, about a hair dryer and a couple of lamps. Never had to replace a main fuse. Bigger wire, yes bigger main, maybe not.