Calculating multi-family dwelling unit service sizes needn’t be a difficult process, but it can be if you don’t follow the right steps
Mlulti-family service calculations can seem confusing, especially since you have a choice of methods standard (Art. 220, Part II) and optional (Art. 220, Part III). But clearing up that confusion is easy once you break them down into their component steps. Deciding which method to use is the hard part. On electrical exams, use the standard method unless the question specifies the optional method.