Space heating air conditioning requirement for optional multifamily dwelling service calc 220.84

[dissonant]

I'm designing a few multifamily dwellings and I would like to use the 220.84 optional calculation as the demand factors give the lower service requirements than the standard calculation. My questions are regarding #3 of where this calc is permissible to be used, which is the requirement that each dwelling have either space heading or air conditioning.

Can I use this calc when there is a single window AC unit for each dwelling? The NEC doesn't specify whether all spaces within each dwelling need air conditioning. So I'm assuming as long as there is at least one conditioned space within each dwelling then I can use this optional calc?

For a multifamily dwelling units without AC, can I factor in a future AC load in order to use this optional calc?

 

[Dennis Alwon]

That is a good question and by the wording in the NEC it appears you can but I question whether that was the intent.(A) Feeder or Service Load.It shall be permissible to calculate the load of a feeder or service that supplies three or more dwelling units of a multifamily dwelling in accordance with Table 220.84 instead of Part III of this article if all the following conditions are met:

• (A) Feeder or Service Load.
  
  
  
  It shall be permissible to calculate the load of a feeder or service that supplies three or more dwelling units of a multifamily dwelling in accordance with Table 220.84 instead of Part III of this article if all the following conditions are met:
  • (1)
    No dwelling unit is supplied by more than one feeder.
  • (2)
    Each dwelling unit is equipped with electric cooking equipment.
    Exception:
    When the calculated load for multifamily dwellings without electric cooking in Part III of this article exceeds that calculated under Part IV for the identical load plus electric cooking (based on 8 kW per unit), the lesser of the two loads shall be permitted to be used.
    
    
  • (3)
    Each dwelling unit is equipped with either electric space heating or air conditioning, or both. Feeders and service conductors whose calculated load is determined by this optional calculation shall be permitted to have the neutral load determined by 220.61.