This text from '08 NEC 220.61 (b)(1) the key word is 'household'
(1) A feeder or service supplying household electric ranges, wall-mounted ovens, counter-mounted cooking units, and electric dryers, where the maximum unbalanced load has been determined in accordance with Table 220.55 for ranges and Table 220.54 for dryers
IMHO, you cannot use this for storage units.
That all said, what type of loads would you have in a storage unit?
Common wiring methods for apartment 'sub-panels' is SER.