NFPA 70: National Electrical Code (NEC), 2014 Chapter 2 ...

1 11/12/2015 nfpa 70 : National Electrical Code (NEC), 2014 eLibrary > nfpa 70 : National Electrical Code (NEC) > Section 220 nfpa 70 : National Electrical Code (NEC), 2014 Chapter 2: Wiring and ProtectionSection 220: Branch-Circuit, Feeder, and Service CalculationsARTICLE 220 Branch-Circuit, Feeder, and Service CalculationsI. Scope. This article provides requirements for calculating branch-circuit, feeder, and service loads. Part Iprovides for general requirements for calculation methods. Part II provides calculation methods for branch-circuit loads. Parts III and IV provide calculation methods for feeders and services.

2 Part V provides calculationmethods for Note No. 1: See examples in Informative Annex Note No. 2: See Figure for information on the organization of Article Branch-Circuit, Feeder, and Service Load Calculation Application of Other Articles. In other articles applying to the calculation of loads in specializedapplications, there are requirements provided in Table that are in addition to, or modifications of, thosewithin this Additional Load Calculation ReferencesCalculationArticleSection (or Part)Air-conditioning and refrigeratingequipment, branch-circuit conductor sizing440 Part IVCranes and hoists, rating and size vehicle charging system branch-circuit and feeder welders, ampacity , 70.

3 National Electrical Code (NEC), 2014 driven or controlled (A), (A)Electrified truck parking space626 Electrolytic cell (C)Electroplating, branch-circuit feeder demand pumps, voltage drop (mandatorycalculation) electric heating equipment forpipelines and vessels, branch-circuit electric space-heating equipment,branch-circuit outdoor electric deicing and snow-melting equipment, branch-circuit machinery, supply (A)Marinas and boatyards, feeder and serviceload homes, manufactured homes, andmobile home parks, total load fordetermining power (B)Mobile homes, manufactured homes, andmobile home parks, allowable demandfactors for park Electrical wiring picture and television studios andsimilar locations sizing of feederconductors for television studio , feeder demand , multimotor and , several motors or a motor(s) andother load(s) 600-volt branch-circuit (B)Over 600-volt feeder (B)Phase converters, vehicle parks, basis (A)Sensitive Electrical equipment, voltage drop(mandatory calculation) (D)Solar photovoltaic systems, circuit sizingand water (E)Theaters, stage switchboard Calculations.

4 (A) Voltages. Unless other voltages are specified, for purposes of calculating branch-circuit and feeder loads,nominal system voltages of 120, 120/240, 208Y/120, 240, 347, 480Y/277, 480, 600Y/347, and 600 volts shall 70: National Electrical Code (NEC), 2014 (1) (2) (3) (B) Fractions of an Ampere. Calculations shall be permitted to be rounded to the nearest whole ampere,with decimal fractions smaller than Branch-Circuit Load General. Branch-circuit loads shall be calculated as shown in , , and Lighting Load for Specified Occupancies. A unit load of not less than that specified in Table occupancies specified therein shall constitute the minimum lighting load.

5 The floor area for each floorshall be calculated from the outside dimensions of the building, dwelling unit, or other area involved. Fordwelling units, the calculated floor area shall not include open porches, garages, or unused or unfinishedspaces not adaptable for future Note: The unit values herein are based on minimum load conditions and 100 percent powerfactor and may not provide sufficient capacity for the installation : Where the building is designed and constructed to comply with an energy code adopted by thelocal authority, the lighting load shall be permitted to be calculated at the values specified in the energy codewhere the following conditions are met.

6 A power monitoring system is installed that will provide continuous information regarding the totalgeneral lighting load of the power monitoring system will be set with alarm values to alert the building owner or manager ifthe lighting load exceeds the values set by the energy demand factors specified in are not applied to the general lighting General Lighting Loads by OccupancyType of OccupancyUnit LoadVolt-Amperes/Square MeterVolt-Amperes/Square FootArmories and auditoriums111 Banks39b3 bBarber shops and beauty parlors333 Churches111 Clubs222 Court rooms222 Dwelling unitsa333 Garages commercial (storage) 6 Hospitals222 Hotels and motels, including apartment houses withoutprovision for cooking by tenantsa222 Industrial commercial (loft) buildings222 Lodge rooms171 Office buildings39b3 bRestaurants222 Schools333 Stores333 Warehouses (storage) 3 In any of the preceding occupancies except one-familydwellings and individual dwelling units of two-familyand multifamily dwellings:11/12/2015 nfpa 70 : National Electrical Code (NEC), 2014 (1) (2) (1) (2) (1) Assembly halls and auditoriums111 Halls, corridors, closets, stairways 6 Storage spaces 3 aSee (J).

7 BSee (K). Other Loads All Occupancies. In all occupancies, the minimum load for each outlet for general-use receptacles and outlets not used for general illumination shall not be less than that calculated (A) through (L), the loads shown being based on nominal branch-circuit : The loads of outlets serving switchboards and switching frames in telephone exchanges shall bewaived from the calculations.(A) Specific Appliances or Loads. An outlet for a specific appliance or other load not covered in (B)through (L) shall be calculated based on the ampere rating of the appliance or load served.(B) Electric Dryers and Electric Cooking Appliances in Dwellings and Household Cooking AppliancesUsed in Instructional Programs.

8 Load calculations shall be permitted as specified in for electricdryers and in for electric ranges and other cooking appliances.(C) Motor Outlets. Loads for motor outlets shall be calculated in accordance with the requirements , , and (D) Luminaires. An outlet supplying luminaire(s) shall be calculated based on the maximum volt-ampererating of the equipment and lamps for which the luminaire(s) is rated.(E) Heavy-Duty Lampholders. Outlets for heavy-duty lampholders shall be calculated at a minimum of 600volt-amperes.(F) Sign and Outline Lighting. Sign and outline lighting outlets shall be calculated at a minimum of 1200volt-amperes for each required branch circuit specified in (A).

9 (G) Show Windows. Show windows shall be calculated in accordance with either of the following:The unit load per outlet as required in other provisions of this sectionAt 200 volt-amperes per 300 mm (1 ft) of show window(H) Fixed Multioutlet Assemblies. Fixed multioutlet assemblies used in other than dwelling units or theguest rooms or guest suites of hotels or motels shall be calculated in accordance with (H)(1) or (H)(2). For thepurposes of this section, the calculation shall be permitted to be based on the portion that containsreceptacle appliances are unlikely to be used simultaneously, each m (5 ft) or fraction thereof of eachseparate and continuous length shall be considered as one outlet of not less than 180 appliances are likely to be used simultaneously, each 300 mm (1 ft) or fraction thereof shall beconsidered as an outlet of not less than 180 volt-amperes.

10 (I) Receptacle Outlets. Except as covered in (J) and (K), receptacle outlets shall be calculated at notless than 180 volt-amperes for each single or for each multiple receptacle on one yoke. A single piece ofequipment consisting of a multiple receptacle comprised of four or more receptacles shall be calculated atnot less than 90 volt-amperes per receptacle. This provision shall not be applicable to the receptacle outletsspecified in (C)(1) and (C)(2).(J) Dwelling Occupancies. In one-family, two-family, and multifamily dwellings and in guest rooms or guestsuites of hotels and motels, the outlets specified in (J)(1), (J)(2), and (J)(3) are included in the general lightingload calculations of No additional load calculations shall be required for such general-use receptacle outlets of 20-ampere rating or less, including receptacles connected to thecircuits in (C)(3)11/12/2015 nfpa 70 .