BRANCH-CIRCUIT, FEEDER, AND SERVICE CALCS 70-61

(3) Each dwelling unit is equipped with either electric space heating or air conditioning or both. Feeders and service-entrance conductors whose demand load is determined by this optional calculation shall be permitted to have the neutral load determined by Section 220-22. (b) House Loads. House loads shall be computed in accordance with Part B of this article and shall be in addition to the dwelling unit loads computed in accordance with Table 220-32. (c) Connected Loads. The connected load to which the demand factors of Table 220-32 apply shall include the following: (1) 1500 volt-amperes for each 2-wire, 20-ampere small appliance branch circuit and each laundry branch circuit specified in Section 220-16. (2) 3 volt-amperes per square foot (0.093 sq m) for general lighting and general-use receptacles. (3) The nameplate rating of all appliances that are fastened in place, permanently connected or located to be on a specific circuit, ranges, wallmounted ovens, counter-mounted cooking units, clothes dryers, water heaters, and space heaters. Table 220-32. Optional Calculation-Demand Factors for Three or More Multifamily Dwelling Units Number of Demand Dwelling Factor Units Percent 3-5 45 6-7 44 8-10 43 11 42 12-13 41 14-15 40 16-17 39 18-20 38 21 37 22-23 36 24-25 35 26-27 34 28-30 33 31 32 32-33 31 34-36 30 37-38 29 39-42 28 43-45 27 46-50 26 51-55 25 56-61 24 62 and over 23 70-62 NATIONAL ELECTRICAL CODE If water heater elements are so interlocked that all elements cannot be used at the same time, the maximum possible load shall be considered the nameplate load. (4) The nameplate ampere or kVA rating of all motors and of all lowpower-factor loads. (5) The larger of the air-conditioning load or the space heating load. 220-33. Optional Calculation - Two Dwelling Units. Where two dwelling units are supplied by a single feeder and the computed load under Part B of this article exceeds that for three identical units computed under Section 220-32, the lesser of the two loads shall be permitted to be used. 220-34. Optional Method - Schools. The calculation of a feeder or service load for schools shall be permitted in accordance with Table 220-34 in lieu of Part B of this article where equipped with electric space heating or air conditioning, or both. The connected load to which the demand factors of Table 220-34 apply shall include all of the interior and exterior lighting, power, water heating, cooking, other loads, and the larger of the air-conditioning load or space heating load within the building or structure. Feeders and service-entrance conductors whose demand load is determined by this optional calculation shall be permitted to have the neutral load determined by Section 220-22. Where the building or structure load is calculated by this optional method, feeders within the building or structure shall have ampacity as permitted in Part B of this article; however, the ampacity of an individual feeder need not be larger than the ampacity for the entire building. This section shall not apply to portable classroom buildings. Table 220-34. Optional Method-Demand Factors for Feeders and Service-Entrance Conductors for Schools Connected Load Demand Factors Volt-Amperes per Square Foot Percent Connected load up to and including 3, plus 100 Conected load over 3 and including 20, plus 75 Connected load over 20 at 25 For SI units: one square foot = 0.093 square meter. 220-35. Optional Calculations for Additional Loads to Existing Installations. For the purpose of allowing additional loads to be connected to existing feeders and services, it shall be permitted to use actual maximum kVA demand figures to determine the existing load on a service or feeder when all the following conditions are met: (1) The maximum demand data is available in kVA for a minimum of a one-year period.