BRANCH-CIRCUIT, FEEDER, AND SERVICE CALCS 70-53

220-4. Branch Circuits Required. Branch circuits for lighting and for appliances, including motor-operated appliances, shall be provided to supply the loads computed in accordance with Section 220-3. In addition, branch circuits shall be provided for specific loads not covered by Section 220-3 where required elsewhere in this Code; for small appliance loads as specified in (b) below; and for laundry loads as specified in (c) below. (a) Number of Branch Circuits. The minimum number of branch circuits shall be determined from the total computed load and the size or rating of the circuits used. In all installations, the number of circuits shall be sufficient to supply the load served. In no case shall the load on any circuit exceed the maximum specified by Section 210-22. (b) Small Appliance Branch Circuits - Dwelling Unit. In addition to the number of branch circuits determined in accordance with (a) above, two or more 20-ampere small appliance branch circuits shall be provided for all receptacle outlets specified by Section 210-52 for the small appliance loads. (c) Laundry Branch Circuits - Dwelling Unit. In addition to the number of branch circuits determined in accordance with (a) and (b) above, at least one additional 20-ampere branch circuit shall be provided to supply the laundry receptacle outlet(s) required by Section 210-52(f). This circuit shall have no other outlets. (d) Load Evenly Proportioned Among Branch Circuits. Where the load is computed on a volt-amperes-per-square-foot (0.093-sq m) basis, the wiring system up to and including the branch-circuit panelboard(s) shall be provided to serve not less than the calculated load. This load shall be evenly proportioned among multioutlet branch circuits within the panelboard(s). Branch-circuit overcurrent devices and circuits need only be installed to serve the connected load. (FPN): See Examples 1(a), 1(b), 2(b), and 4(a), Chapter 9. B. Feeders 220-10. General. (a) Ampacity and Computed Loads. Feeder conductors shall have sufficient ampacity to supply the load served. In no case shall the computed load of a feeder be less than the sum of the loads on the branch circuits supplied as determined by Part A of this article after any applicable demand factors permitted by Parts B, C, or D have been applied. (FPN): See Examples 1 through 10, Chapter 9. See Section 210-22(b) for maximum load in amperes permitted for lighting units operating at less than 100 percent power factor. (b) Continuous and Noncontinuous Loads. Where a feeder supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device shall not be less than the noncontinuous load plus 125 percent of the continuous load. 70-54 NATIONAL ELECTRICAL CODE Exception: Where the assembly including the overcurrent devices protecting the feeder(s) are listed for operation at 100 percent of their rating, neither the ampere rating of the overcurrent device nor the ampacity of the feeder conductors shall be less than the sum of the continuous load plus the noncontinuous load. 220-11. General Lighting. The demand factors listed in Table 220-11 shall apply to that portion of the total branch-circuit load computed for general illumination. They shall not be applied in determining the number of branch circuits for general illumination. (FPN): See Section 220-16 for application of demand factors to small appliance and laundry loads in dwellings. Table 220-11. Lighting Load Feeder Demand Factors Portion of Lighting Load Demand to which Demand Factor Type of Occupancy Factor Applies (volt-amperes) Percent Dwelling Units First 3000 or less at 100 From 3001 to 120,000 at 35 Remainder over 120,000 at 25 Hospitals* First 50,000 or less at 40 Remainder over 50,000 at 20 Hotels and Motels - Including Apartment Houses without First 20,000 or less at 50 Provision for Cooking by From 20,001 to 100,000 at 40 Tenants* Remainder over 100,000 at 30 Warehouses First 12,500 or less at 100 (Storage) Remainder over 12,500 at 50 All Others Total volt-amperes 100 *The demand factors of this table shall not apply to the computed load of feeders to areas in hospitals, hotels, and motels where the entire lighting is likely to be used at one time, as in operating rooms, ballrooms, or dining rooms. 220-12. Show-Window Lighting. For show-window lighting, a load of not less than 200 volt-amperes shall be included for each linear foot (305 mm) of show window, measured horizontally along its base. (FPN): See Section 220-3(c), Exception No. 3, for branch circuits supplying show windows. 220-13. Receptacle Loads - Nondwelling Units. In other than dwelling units, receptacle loads computed at not more than 180 volt-amperes per outlet in accordance with Section 220-3(c)(6) shall be permitted to be added to the lighting loads and made subject to the demand factors given in Table 220-11, or they shall be permitted to be made subject to the demand factors given in Table 220-13.