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gging, or other approved means; each ungrounded conductor of 6 AWG or smaller shall be identified by polarity at all termination, connection, and splice points in compliance with 215.12(C)(2)(a) and (C)(2)(b). The identification methods utilized for conductors originating within each feeder panelboa...

gging, or other approved means; each ungrounded conductor of 6 AWG or smaller shall be identified by polarity at all termination, connection, and splice points in compliance with 215.12(C)(2)(a) and (C)(2)(b). The identification methods utilized for conductors originating within each feeder panelboard or similar feeder distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each feeder panelboard or similar feeder distribution equipment. * (a) Positive Polarity, Sizes 6 AWG or Smaller. Where the positive polarity of a dc system does not serve as the connection for the grounded conductor, each positive ungrounded conductor shall be identified by one of the following means: o (1) A continuous red outer finish o (2) A continuous red stripe durably marked along the conductor’s entire length on insulation of a color other than green, white, gray, or black o (3) Imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black, and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.8(B) o (4) An approved permanent marking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black * (b) Negative Polarity, Sizes 6 AWG or Smaller. Where the negative polarity of a dc system does not serve as the connection for the grounded conductor, each negative ungrounded conductor shall be identified by one of the following means: o (1) A continuous black outer finish o (2) A continuous black stripe durably marked along the conductor’s entire length on insulation of a color other than green, white, gray, or red o (3) Imprinted minus signs (-) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red, and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.8(B) o (4) An approved permanent marking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted minus signs (-) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red 215.15 Barriers. Barriers shall be placed such that no energized, uninsulated, ungrounded busbar or terminal is exposed to inadvertent contact by persons or maintenance equipment while servicing load terminations in panelboards, switchboards, switchgear, or motor control centers supplied by feeder taps in 240.21(B) or transformer secondary conductors in 240.21(C) when the disconnecting device, to which the tap conductors are terminated, is in the open position. 215.18 Surge Protection. (A) Surge-Protective Device. Where a feeder supplies any of the following, a surge-protective device (SPD) shall be installed: * (1) Dwelling units * (2) Dormitory units * (3) Guest rooms and guest suites of hotels and motels * (4) Areas of nursing homes and limited-care facilities used exclusively as patient sleeping rooms (B) Location. The SPD shall be installed in or adjacent to distribution equipment, connected to the load side of the feeder, that contains branch circuit overcurrent protective device(s) that supply the locations specified in 215.18(A). Informational Note: Surge protection is most effective when closest to the branch circuit. Surges can be generated from multiple sources including, but not limited to, lightning, the electric utility, or utilization equipment. (C) Type. The SPD shall be a Type 1 or Type 2 SPD. (D) Replacement. Where the distribution equipment supplied by the feeder is replaced, all of the requirements of this section shall apply. (E) Ratings. SPDs shall have a nominal discharge current rating (In) of not less than 10kA. Article 220 Branch-Circuit, Feeder, and Service Load Calculations Part I. General 220.1 Scope. This article provides requirements for calculating branch-circuit, feeder, and service loads. Part I provides general requirements for calculation methods. Part II provides calculation methods for branch-circuit loads. Part III and Part IV provide calculation methods for feeder and service loads. Part V provides calculation methods for farm loads. Part VI provides calculation methods for health care facilities. Part VII provides calculation methods for marinas, boatyards, floating buildings, and commercial and noncommercial docking facilities. Informational Note No. 1: See Informative Annex D for examples. Informational Note No. 2: See Informational Note Figure 220.1 for information on the organization of this article. Informational Note Figure 220.1 Branch-Circuit, Feeder, and Service Load Calculation Methods. ENHANCED CONTENT Collapse Although this article does not contain the requirements for determining the minimum number of branch circuits, the loads calculated in accordance with Article 220 are used in conjunction with the rules of 210.11 to determine how many branch circuits are needed at a premises. See 210.11(A) for the general requirement on determining the minimum number of branch circuits for all occupancy types. 220.3 Other Articles for Specific-Purpose Calculations. Table 220.3 shall provide references for specific-purpose calculation requirements not located in Chapters 5, 6, or 7 that amend or supplement the requirements of this article. Table 220.3 Specific-Purpose Calculation References Calculation Article Section (or Part) Air-conditioning and refrigerating equipment, branch-circuit conductor sizing 440 Part IV Capacitors 460 460.8 Fixed electric heating equipment for pipelines and vessels, branch-circuit sizing 427 427.4 Fixed electric space-heating equipment, branch-circuit sizing 424 424.3 Fixed outdoor electric deicing and snow-melting equipment, branch-circuit sizing 426 426.4 Fixed resistance and electrode industrial process heating equipment 425 425.4 Motors, feeder demand factor 430 430.26 Motors, multimotor and combination-load equipment 430 430.25 Motors, several motors or a motor(s) and other load(s) 430 430.24 Over 1000-volt ac and 1500-volt dc branch-circuit calculations 235 235.19 Over 1000-volt feeder calculations 215 215.2(B) Phase converters, conductors 455 455.6 Storage-type water heaters 422 422.11 220.5 Calculations. ENHANCED CONTENT Collapse For uniform calculation of load, nominal voltages, as listed in 220.5(A), are required to be used in computing the ampere load on the conductors. Loads are calculated on the basis of volt-amperes (VA) or kilovolt-amperes (kVA), rather than watts or kilowatts (kW), to calculate the true ampere values. However, the rating of equipment is given in watts or kilowatts for resistive loads. Such ratings are considered to be the equivalent of the same rating in volt-amperes or kilovolt-amperes. This concept recognizes that load calculations determine conductor and circuit sizes, that the power factor of the load is often unknown, and that the conductor “sees” the circuit volt- amperes only, not the circuit power (watts). See also 310.15 to select conductor sizes using the ampacity tables. For examples of load calculations, see Informative Annex D. (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 be used. (B) Fractions of an Ampere. Calculations shall be permitted to be rounded to the nearest whole ampere, with decimal fractions smaller than 0.5 dropped. (C) Floor Area. The floor area for each floor shall be calculated from the outside dimensions of the building, dwelling unit, or other area involved. For dwelling units, the calculated floor area shall not include open porches or unfinished areas not adaptable for future use as a habitable room or occupiable space. Part II. Branch-Circuit Load Calculations 220.10 General. Branch-circuit loads shall be calculated in accordance with the following sections: * (1) 220.14 for other loads - all occupancies * (2) 220.16 for additions to existing installations * (3) 220.41 for dwelling units * (4) 220.42 for lighting loads for non-dwelling occupancies * (5) 220.44 for hotel and motel occupancies 220.11 Maximum Load. The total load on a branch circuit shall not exceed the rating of the branch circuit nor the maximum loads specified in 220.11(A) through (C) under the conditions specified therein. (A) Motor-Operated and Combination Loads. Where a circuit supplies only motor-operated loads, the conductor sizing requirement specified in 430.22 shall apply. Where a circuit supplies only air- conditioning equipment, refrigerating equipment, or both, the requirements of 440.6 shall apply. For circuits supplying loads consisting of motor-operated utilization equipment that is fastened in place and has a motor larger than 1/8 hp in combination with other loads, the total calculated load shall be based on 125 percent of the largest motor load plus the sum of the other loads in accordance with 430.24. (B) Inductive and LED Lighting Loads. For circuits supplying lighting units that have ballasts, transformers, autotransformers, or LED drivers, the calculated load shall be based on the total ampere ratings of such units and not on the total watts of the lamps. (C) Electric Cooking Appliances. Applying demand factors for ranges, wall-mounted ovens, counter-mounted cooking units, and other household cooking appliance loads in excess of 13/4 kW shall be permitted in accordance with Table 220.55, including Notes 4, 5, and 6. 220.14 Other Loads - All Occupancies. Branch-circuit load calculations shall include calculation of a minimum load on each outlet as calculated in 220.14(A) through (K) and then summed to establish the load on the branch circuit. 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 in 220.14(A) through (K), with the loads shown being based on nominal branch-circuit voltages. Exception: The loads of outlets serving switchboards and switching frames in telephone exchanges shall be waived from the calculations. (A) Specific Appliances or Loads. An outlet for a specific appliance or other load not covered in 220.14(B) through (K) 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 Appliances Used in Instructional Programs. Load calculations shall be permitted as specified in 220.54 for electric dryers and in 220.55 for electric ranges and other cooking appliances. (C) Motor Outlets. The conductor sizing requirements specified in 430.22, 430.24, and 440.6 shall be used to determine the loads for motor outlets. (D) Luminaires. An outlet supplying a luminaire(s) shall be calculated based on the maximum volt-ampere rating of the equipment and lamps for which the luminaire(s) is rated. ENHANCED CONTENT Collapse Where the rating of the luminaires installed for general lighting exceeds the minimum load provided for in Table 220.42(A), the minimum general lighting load for that premises must be based on the installed luminaires. In general, no additional calculation is required for luminaires (recessed and surface mounted) installed in or on a dwelling unit, because the load of such luminaires is covered in the 3 volt-amperes per square foot calculation specified in 220.41. (E) Heavy-Duty Lampholders. Outlets for heavy-duty lampholders shall be calculated at a minimum of 600 volt-amperes. (F) Sign and Outline Lighting. Sign and outline lighting outlets shall be calculated at a minimum of 1200 volt- amperes for each required branch circuit specified in 600.5(A). ENHANCED CONTENT Collapse The load calculation must be based on a minimum of 1200 volt-amperes or the actual load of the sign and outline lighting outlets, whichever is greater. (G) Show Windows. Show windows shall be calculated in accordance with either of the following: * (1) The unit load per outlet as required in other provisions of this section * (2) At 200 volt-amperes per linear 300 mm (1 ft) of show window ENHANCED CONTENT Collapse The linear-foot calculation method is permitted in lieu of the specified unit load per outlet for branch circuits serving show windows. The exhibit below shows an example of the volt-ampere per linear-foot load calculation for branch circuits serving a show window. Fixed Multioutlet Assemblies. Fixed multioutlet assemblies used in other than dwelling units or the guest rooms or guest suites of hotels or motels shall be calculated in accordance with the following: Where appliances are unlikely to be used simultaneously, each 1.5 m (5 ft) or fraction thereof of each separate and continuous length shall be considered as one outlet of not less than 180 volt-amperes. Where appliances are likely to be used simultaneously, each 300 mm (1 ft) or fraction thereof shall be considered as an outlet of not less than 180 volt-amperes. For the purposes of this section, the calculation shall be permitted to be based on the portion that contains receptacles. ENHANCED CONTENT Collapse In light-use commercial and industrial applications, not all the cord-connected equipment is expected to be used at the same time. An example of light use is a workbench area where one worker uses one electrical tool at a time. In heavy-use applications, all the cord-connected equipment generally is operating at the same time. An example of heavy use is a retail store displaying television sets, where most or all sets are operating simultaneously. The exhibit below illustrates the difference between items (1) and (2) of 220.14(H). See also 220.47 for demand factors that apply to the load calculation in 220.14(H) and (I). (I) Receptacle Outlets. Except as covered in 220.41 and 220.14(J), receptacle outlets shall be calculated at not less than 180 volt-amperes for each single or for each multiple receptacle on one yoke. A single piece of equipment consisting of a multiple receptacle comprised of four or more receptacles shall be calculated at not less than 90 volt-amperes per receptacle. This provision shall not be applicable to the receptacle outlets specified in 210.11(C)(1) and (C)(2). ENHANCED CONTENT Collapse Section 220.47 contains demand factors that apply to the load calculation in 220.14(H) and (I). In dwelling units, the minimum unit load for receptacles supplied by general-purpose branch circuits is specified in 220.41 and is based on floor area rather than an assigned load per receptacle outlet. The load requirements for the laundry and small-appliance branch circuits are 1500 voltamperes per circuit, as described in 220.52. The following exhibit shows the load of 180 volt-amperes applied to single and multiple receptacles mounted on a single yoke or strap, and the load of 360 volt-amperes applied to the outlet containing two duplex receptacles and to the outlet containing the device with four receptacles. Note that the last outlet of the top circuit consists of two duplex receptacles on separate straps. The multiple receptacle supplied from the bottom circuit in the exhibit consists of four receptacles. For example, single-strap and multiple-receptacle devices are calculated as follows: In the exhibit below, the maximum number of receptacle outlets permitted on 15- and 20-ampere branch circuits is 10 and 13 outlets, respectively, based on the load assigned for each outlet by 220.14(I). This restriction does not apply to receptacle outlets in dwelling occupancies. Receptacle Outlets in Office Buildings. In office buildings, the receptacle loads shall be calculated to be the larger of the following: The calculated load from 220.14(I) 11 volt-amperes/m2 (1 volt-ampere/ft2) Other Outlets. Other outlets not covered in 220.14(A) through (J) shall be calculated based on 180 volt-amperes per outlet. 220.16 Loads for Additions to Existing Installations. (A) Dwelling Units. Loads added to an existing dwelling unit(s) shall comply with the following as applicable: * (1) Loads for structural additions to an existing dwelling unit or for a previously unwired portion of an existing dwelling unit shall be calculated in accordance with 220.14. * (2) Loads for new circuits or extended circuits in previously wired dwelling units shall be calculated in accordance with 220.14. (B) Other Than Dwelling Units. Loads for new circuits or extended circuits in other than dwelling units shall be calculated in accordance with either 220.42 or 220.14, as applicable. Part III. Feeder and Service Load Calculations 220.40 General. The calculated load of a feeder or service shall not be less than the sum of the loads on the branch circuits supplied, as determined by Part II of this article, after any applicable demand factors permitted or required by Part III, IV, V, VI, or VII have been applied. Informational Note No. 1: See Informative Annex D, Examples D1(a) through D10, for examples of feeder and service load calculations. Informational Note No. 2: See 220.11(B) for the maximum load in amperes permitted for lighting units operating at less than 100 percent power factor. ENHANCED CONTENT Collapse In the exhibit shown below, each panelboard supplies a calculated load of 80 amperes. The main set of service conductors is sized to carry the total calculated load of 240 amperes (3 x 80 A). The service conductors from the meter enclosure to each panelboard (2 AWG Cu = 95 A per 60øC column of Table 310.16) are sized to supply a calculated load of 80 amperes and to meet the requirement of 230.90 relative to overcurrent (overload) protection of service conductors terminating in a single-service overcurrent protective device. The main set of service conductors (250 kcmil THWN Cu = 255 A per 75øC column of Table 310.16) is not required to be sized to carry 300 amperes based on the combined rating of the panelboards. The individual service- entrance conductors to each panelboard (2 AWG THWN) meet the requirement of 230.90. See also 230.23, 230.31, and 230.42 for specifics on size and rating of service conductors. 220.41 Dwelling Units, Minimum Unit Load. In one-family, two-family, and multifamily dwellings, the minimum unit load shall be not less than 33 volt-amperes/m2 (3 volt-amperes/ft2). Unit loads include the following lighting and receptacle outlets, and no additional load calculations shall be required: * (1) All general-use receptacle outlets of 20-ampere rating or less, including receptacles connected to the circuits specified in 210.11(C)(3) and (C)(4) * (2) The receptacle outlets specified in 210.52(E) and (G) * (3) The lighting outlets specified in 210.70 The minimum lighting load shall be determined using the minimum unit load and the floor area as determined in 220.5(C) for dwelling occupancies. Motors rated less than 1/8 hp and connected to a lighting circuit shall be considered part of the minimum lighting load. 220.42 Lighting Load for Non-Dwelling Occupancies. (A) General. A unit load of not less than that specified in Table 220.42(A) for non-dwelling occupancies and the floor area determined in 220.5(C) shall be used to calculate the minimum lighting load. Motors rated less than 1/8 HP and connected to a lighting circuit shall be considered general lighting load. Informational Note: The unit values of Table 220.42(A) are based on minimum load conditions and 80 percent power factor and might not provide sufficient capacity for the installation contemplated. Table 220.42(A) General Lighting Loads by Non-Dwelling Occupancy Type of Occupancy Unit Load Volt-amperes/ m2 Volt-amperes/ ft2 Automotive facility 16 1.5 Convention center 15 1.4 Courthouse 15 1.4 Dormitory 16 1.5 Exercise center 15 1.4 Fire station 14 1.3 Gymnasium1 18 1.7 Health care clinic 17 1.6 Hospital 17 1.6 Hotel or motel, or apartment house without provisions for cooking by tenants2 18 1.7 Library 16 1.5 Manufacturing facility3 24 2.2 Motion picture theater 17 1.6 Museum 17 1.6 Office4 14 1.3 Parking garage5 3 0.3 Penitentiary 13 1.2 Performing arts theater 16 1.5 Police station 14 1.3 Post office 17 1.6 Religious facility 24 2.2 Restaurant6 16 1.5 Retail7, 8 20 1.9 School/university 16 1.5 Sports arena 16 1.5 Town hall 15 1.4 Transportation 13 1.2 Warehouse 13 1.2 Workshop 18 1.7 Note: The 125 percent multiplier for a continuous load as specified in 210.20(A) is included, therefore no additional multiplier shall be required when using the unit loads in this table for calculating the minimum lighting load for a specified occupancy. 1 Armories and auditoriums are considered gymnasium-type occupancies. 2 Lodge rooms are similar to hotels and motels. 3 Industrial commercial loft buildings are considered manufacturing-type occupancies. 4 Banks are office-type occupancies. 5 Commercial (storage) garages are considered parking garage occupancies. 6 Clubs are considered restaurant occupancies. 7 Barber shops and beauty parlors are considered retail occupancies. 8 Stores are considered retail occupancies. (B) Energy Code. Where the building is designed and constructed to comply with an energy code adopted by the local authority, the lighting load shall be permitted to be calculated using the unit values specified in the energy code where the following conditions are met: * (1) A power monitoring system is installed that will provide continuous information regarding the total general lighting load of the building. * (2) The power monitoring system will be set with alarm values to alert the building owner or manager if the lighting load exceeds the values set by the energy code. Automatic means to take action to reduce the connected load shall be permitted. * (3) The demand factors specified in 220.45 are not applied to the general lighting load. * (4) The continuous load multiplier of 125 percent shall be applied. 220.43 Office Buildings. In office buildings, the receptacle loads shall be calculated to be the larger of the following: * (1) The calculated load from 220.14(I) after Table 220.47 demand factors have been applied * (2) 11 volt-amperes/m2 or 1 volt-ampere/ft2 220.44 Hotel and Motel Occupancies. In guest rooms or guest suites of hotels and motels, the following lighting and receptacle outlets are included in the minimum unit load in Table 220.42(A), and no additional load calculations shall be required for such outlets: * (1) All general-use receptacle outlets of 20-ampere rating or less, including receptacles connected to the circuits in 210.11(C)(3) and (C)(4) * (2) The receptacle outlets specified in 210.52(E)(3) * (3) The lighting outlets specified in 210.70 220.45 General Lighting. The demand factors specified in Table 220.45 shall apply to that portion of the total branch-circuit load calculated for general illumination. They shall not be applied in determining the number of branch circuits for general illumination. Table 220.45 Lighting Load Demand Factors Type of Occupancy Portion of Lighting Load to Which Demand Factor Applies (Volt-Amperes) Demand Factor (%) Dwelling units First 3000 at 100 From 3001 to 120,000 at 35 Remainder over 120,000 at 25 Hotels and motels, including apartment houses without provision for cooking by tenants* First 20,000 or less at 60 From 20,001 to 100,000 at 50 Remainder over 100,000 at 35 Warehouses (storage) First 12,500 or less at 100 Remainder over 12,500 at 50 All others Total volt-amperes 100 *The demand factors of this table shall not apply to the calculated load of feeders or services supplying areas in hotels and motels where the entire lighting is likely to be used at one time, as in ballrooms or dining rooms. 220.46 Show-Window and Track Lighting. (A) Show Windows. For show-window lighting, a load of not less than 660 volt-amperes/linear meter or 200 volt-amperes/l