The optional method of calculation for dwelling units is reserved for ___.
dwelling units supplied by service conductors with an ampacity of 100 amperes or greater.
According to Section 220.82(A), the optional method of calculation is permitted only if the dwelling unit service-entrance conductors or feeder conductors have an ampacity of at least 100 amperes. This calculation method applies to a single dwelling unit, whether it is a separate building or located in a multifamily dwelling. It applies to dwellings served by a 120/240- volt, single phase system or a 208Y/120- volt, 3-phase system. Generally, the optional calculation method provides an easier and less complex calculation method than the standard (general) method for computing the total demand load for feeders and service-entrance conductors.
