I. General
220.1 
Scope 
Figure 220.1 indicates the location in this section of the various calculation requirements.
Figure 220.1. Branchcircuit, feeder, and service calculation methods.
220.3 
Application of other Articles 
Table 220.3 lists additional load calculation references for specilized areas.
Calculation 
Article 
Section 

AirConditioning and Refrigerating Equipment, BranchCircuit Conductor Sizing 
440 
Part IV 
Cranes and Hoists, Rating and Size of Conductors 
610 
610.14 
Electric Welders, ampacity calculations 
630 
630.11, 630.31 
Electrically Driven or Controlled Irrigation Machines 
675 
675.7(A), 
Electrolytic Cell Lines 
668 
668.3(C) 
Electroplating, BranchCircuit Conductor Sizing 
669 
669.5 
Elevator Feeder Demand Factors 
620 
620.14 
Fire Pumps, Voltage Drop (mandatory calculation) 
695 
695.7 
Fixed Electric Heating Equipment for Piplines and Vessels, BranchCircuit Sizing 
427 
427.4 
Fixed Electric Space Heating Equipment, BranchCircuit Sizing 
424 
424.3 
Fixed Outdoor Electric Deicing and SnowMelting Equipment, BranchCircuit Sizing 
426 
426.4 
Industrial Machinery, Supply Conductor Sizing 
670 
670.4(A) 
Marinas and Boatyards, Feeder and Service Load Calculations 
555 
555.12 
Mobile Homes, Manufactured Homes, and Mobile Home Parks, Total Load for Determining Power Supply 
550 
550.18(B) 
Mobiles Homes, Manufactured Homes, and Mobile Home Parks, Allowable Demand Factors for Park Electrical Wiring Systems 
550 
550.31 
Motion Picture and Television Studios and Similar LocationsSizing of Feeder Conductors for Television Studio Sets 
530 
530.19 
Motors, Feeder Demand Factor 
430 
430.26 
Motors, Multimotor and CombinationLoad Equipment 
430 
430.25 
Motors, Several Motors or a Motor(s) and Other Load(s) 
430 
430.24 
Over 600 Volt Branch Circuit Calculations 
210 
210.19(B) 
Over 600 Volt Feeder Calculations 
215 
215.2(B) 
Phase Converters, Conductors 
455 
455.6 
Recreational Vehicle Parks, Basis of Calculations 
551 
551.73(A) 
Sensitive Electrical Equipment, Voltage Drop (mandatory calculation) 
647 
647.4(D) 
Solar Photovoltaic Systems, Circuit Sizing and Current 
690 
690.8 
StorageType Water Heaters 
422 
422.11(E) 
Theaters, Stage Switchboard Feeders 
520 
520.27 
220.5 
Calculations 
The nominal voltages to be used for branchcircuit and feeder load calculations are 120, 120/240, 208Y/120, 240, 347, 480Y.277, and 600 unless there are others specified. If there is a fraction of an ampere left when making the calculations, then if the fraction is less than 0.5 it can be dropped.
II. BranchCircuit Load Calculations
220.10 
General 
Sections 220.12, 220.14, and 220.16 are to be used for branch circuit calculations.
220.12 
Lighting Load for Specified Occupancies 
Table 220.12 lists the minimum load required based on floor area, which is calculated using outside dimensions. Where an area cannot be used in dwelling units, garages, and open porches, it does not have to be included. It should be noted that these values are minimum load conditions and 100% power factor and may not provide sufficient capacity for the proposed installation.
Type of Occupancy 
Unit Load 


VoltAmperes per Sq. Meter 
VoltAmperes per Sq. Ft. 

Armories and auditoriums 
11 
1 
Banks 
39[b] 
3½[b] 
Barber shops and beauty parlors 
33 
3 
Churches 
11 
1 
Clubs 
22 
2 
Court rooms 
22 
2 
Dwelling units[a] 
33 
3 
Garagescommercial (storage) 
6 
½ 
Hospitals 
22 
2 
Hotels and motels, including apartment houses without provisions for cooking by tenants[a] 
22 
2 
Industrial commercial (loft) buildings 
22 
2 
Lodge rooms 
17 
1½ 
Office buildings 
39[b] 
3½[b] 
Restaurants 
22 
2 
Schools 
33 
3 
Stores 
33 
3 
Warehouses (storage) 
3 
¼ 
In any of the above occupancies except onefamily dwellings and individual dwelling units of two family and multifamily dwelling units: 

Assembly halls and auditoriums 
11 
1 
Halls, corridors, closets, stairways 
6 
½ 
Storage spaces 
3 
¼ 
[b] See Section 220.14(K).
[a] See Section 220.14(J).
220.14 
Other LoadsAll Occupancies 
There is a list of requirements for all other loads. An outlet for an appliance or other specific load not covered below is to be calculated on the ampere rating of the appliance or load. The load for electric dryers is based on Section 220.54 and electric ranges and other cooking devices on Section 220.55. Motor loads are to be calculated in accordance with Sections 430.22, 430.24, and 440.6. Luminaires (lighting fixtures) are to be calculated based on the maximum voltampere rating of the equipment and lamps. Heavyduty lampholders are calculated at a minimum of 600 VA. Sign and outdoor lighting is to be calculated at a minimum of 1200 VA for each branch circuit noted in Section 600.5(A). Show windows are calculated at 200 VA per linear foot of window or the unit load as noted elsewhere in this section. Multioutlet assemblies need only be counted as one outlet (180 VA) for each 1.5 m (5ft.) length unless many appliances are used simultaneously. If appliances are used simultaneously, then each 1.5 m (1ft.) length is calculated at 180 VA. The portion containing the receptacle outlets can be used for calculations. Receptacle outlets on one strap other than those covered by the calculations in Section 220.14(J) are calculated at 180 VA each. If a single piece of equipment has multiple receptacles, then each receptacle is to be calculated at not less than 90 VA. Receptacles noted in Sections 210.11(C)(1) and (2) are not bound by the previous two sentences. In dwelling occupancies all receptacle outlets as noted in Sections 210.11(C)(3), 210.52(E), 210.52(G), and 210.70(A) and (B) are included in the general lighting load calculations in Section 220.12. In a bank or office building use the larger of either the calculated load of 220.14(I) or 1 voltampere/ft2. All other outlets are calculated at 180 VA.
220.16 
Loads for Additions to Existing Installations 
Loads for additions or unwired portions greater than 46.5 square meters (500 square feet) to dwelling units are to be calculated in accordance with Sections 220.12 and 220.14. Additions to circuits should be calculated as noted in Sections 220.12 and 220.14. Loads for other than dwelling units are to be calculated as noted in Section 220.12 and 220.14.
220.18 
Maximum Loads 
The load should never exceed the rating of the branch circuit. Article 430 applies when only motoroperated loads are used. Article 440 is used for airconditioning and refrigeration equipment. When more than one motor fastened in place is used, then you use 125% of the largest motor and the sum of the rest of the motor loads. Inductive lighting is calculated on the total ampere rating of the unit including ballasts, transformers, lamps, etc. Range load demand factors can be used in accordance with Table 220.55 including note 4.
Number of Appliances 
Demand Factors (Percent) (See Notes) 
Column C Maximum Demand (kW) (See Notes) 


Column A (Less Than 3½ kW Rating) 
Column B (3½ kW to 8¾ kW Rating) 
(Not over 12 kW Rating) 

1 
80 
80 
8 
2 
75 
65 
11 
3 
70 
55 
14 
4 
66 
50 
17 
5 
62 
45 
20 
6 
59 
43 
21 
7 
56 
40 
22 
8 
53 
36 
23 
9 
51 
35 
24 
10 
49 
34 
25 
11 
47 
32 
26 
12 
45 
32 
27 
13 
43 
32 
28 
14 
41 
32 
29 
15 
40 
32 
30 
16 
39 
28 
31 
17 
38 
28 
32 
18 
37 
28 
33 
19 
36 
28 
34 
20 
35 
28 
35 
21 
34 
26 
36 
22 
33 
26 
37 
23 
32 
26 
38 
24 
31 
26 
39 
25 
30 
26 
40 
2630 
30 
24 

3140 
30 
22 

4150 
30 
20 

5160 
30 
18 

61 and over 
30 
16 

Note 1. Over 12 kW through 27 kW ranges all of same rating. For ranges individually rated more than 12 kW but not more than 27 kW, the maximum demand in Column C shall be increased 5 percent for each additional kW of rating or major fraction thereof by which the rating of individual ranges exceeds 12 kW. Note 2. Over 8¾ kW through 27 kW ranges of unequal ratings. For ranges individually rated more than 8¾ kW and of different ratings, but none exceeding 27 kW, an average value of rating shall be calculated by adding together the ratings of all ranges to obtain the total connected load (using 12 kW for any range rated less than 12 kW) and dividing by the total number of ranges. Then the maximum demand in Column C shall be increased 5 percent for each kilowatt or major fraction thereof by which this average value exceeds 12 kW. Note 3. Over 1¾ kW through 8¾ kW. In lieu of the method provided in Column C, it shall be permissible to add the nameplate ratings of all household cooking appliances rated more than 1¾ kW but not more than 8¾ kW and multiply the sum by the demand factors specified in Column A or B for the given number of appliances. Where the rating of cooking appliances falls under both Column A and Column B, the demand factors for each column shall be applied to the appliances for that column, and the results added together. Note 4. BranchCircuit Load. It shall be permissible to calculate the branchcircuit load for one range in accordance with Table 220.55. The branchcircuit load for one wallmounted oven or one countermounted cooking unit shall be the nameplate rating of the appliance. The branchcircuit load for a countermounted cooking unit and not more than two wallmounted ovens, all supplied from a single branch circuit and located in the same room, shall be calculated by adding the nameplate rating of the individual appliances and treating this total as equivalent to one range. Note 5. This table also applies to household cooking appliances rated over 1¾ kW and used in instructional programs. FPN No. 1: See Example D5(a) in Annex D. FPN No. 2: See Table 220.56 for commercial cooking equipment. FPN No. 3: See the examples in Annex D. 
III. Feeders and Services
220.40 
General 
Feeders must be able to supply the required load. They must be sized to supply the connected load with applied allowable demand factors.
220.42 
General Lighting 
To calculate the general lighting load, use the demand factors in Table 220.42.
Type of Occupancy 
Portion of Lighting Load to Which Demand Factor Applies (VoltAmperes) 
Demand Factor Percent 

Dwelling units 
First 3000 or less at 
100 
From 3001 to 120,000 at 
35 

Remainder over 120,000 at 
25 

Hospitals[1] 
First 50,000 or less at 
40 
Remainder over 50,000 at 
20 

Hotels and motelsincluding apartment houses without provision for cooking by tenants1 
First 20,000 or less at 
50 
From 20,001 to 100,000 at 
40 

Remainder over 100,000 at 
30 

Warehouses (storage) 
First 12,500 or less at 
100 
Remainder over 12,500 at 
50 

All others 
Total voltamperes 
100 
[1] The demand factors of this table shall not apply to the calculated load of feeders or services supplying 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.
220.43 
ShowWindow and Track Lighting 
Use at least 660 VA per linear meter or 200 VA per linear foot for show windows and 150 VA for every 600 mm (2 ft.) for track lighting in other than dwelling units or hotels and motels. When multicircuit track is used the load is to be considered divided equally between circuits.
220.44 
Receptacle LoadsNondwelling Units 
If a receptacle load is calculated in accordance with Section 220.14(H) Fixed Multioutlet Assemblies and 220.14(I) Receptacle Outlets, then the demand factors in Table 220.42 or Table 220.44 can be used.
Portion of Receptacle Load to Which Demand Factor Applies (VoltAmperes) 
Demand Factor Percent 

First 10 kVA or less 
100 
Remainder over 10 kVA at 
50 
220.50 
Motors 
Calculate motor loads as directed by Sections 430.24, 430.25, and 430.26 and 440.6 for hermetic refrigerant motor compressors.
220.51 
Fixed Electric Space Heating 
Generally, the load is to be calculated at 100% of the connected load. In no case can the service or feeder current rating be less than that of the largest branch circuit supplied. If, however, the total load is less as a result of intermittent operation or diversity, the authorities can reduce the calculated load provided the conductors have a rating for the determined load.
220.52 
Small Appliance and Laundry LoadsDwelling Units 
(A) SmallAppliance Circuit Load. Use 1500VA for each twowire smallappliance branch circuit that is required in 210.11(C)(1). When the load is divided through two or more feeders, use 1500VA for each twowire smallappliance branch circuit. This load can be included in the general lighting load and demand factors of Table 220.42 can be applied.
(B) Laundry Circuit Load. Use not less than 1500VA for each twowire laundry branch circuit that is required in 210.11(C)(2). This load can be included in the general lighting load and demand factors of Table 220.42.
220.53 
Appliance LoadDwelling Units 
A demand factor of 75% can be applied to nameplate ratings of four or more appliances in a dwelling supplied by the same feeder or service. This does not apply to electric ranges, clothes dryers, and space heating or airconditioning equipment.
220.54 
Electric Clothes DryersDwelling Units 
Use a load of 5000 watts (voltamperes) or the nameplate rating, whichever is larger. Demand factors listed in Table 220.54 can be used. If two or more singlephase dryers are served by a threephase fourwire circuit, the total load is calculated at twice the maximum number connected between two phases.
Number of Dryers 
Demand Factor Percent 

14 
100 
5 
85 
6 
75 
7 
65 
8 
60 
9 
55 
10 
50 
11 
47 
1222 
[47(number of 
23 
35 
2442 
[350.5(number of 
43 and over 
25 
220.55 
Electric Ranges and Other Cooking AppliancesDwelling Unit(s) 
The load for household electric ranges, wallmounted ovens, countermounted cooking units, and other household cooking units larger than 1¾ kW are shown in Table 220.55. kVA and kW are considered equivalent for this section.
For singlephase ranges on a threephase fourwire feeder or service, use twice the number of units between two phases.
220.56 
Kitchen EquipmentOther Than Dwelling Units 
This section applies to commercial cooking equipment, dishwasher booster heaters, water heaters, and other kitchen equipment. Demand factors shown in Table 220.56 can be used. They apply to thermostatic controlled or intermittently used kitchen equipment, not air conditioning, space heating or ventilating equipment. The feeder or service must always be larger than the sum of the two largest kitchen equipment loads.
Number of Units of Equipment 
Demand Factors (Percent) 

1 
100 
2 
100 
3 
90 
4 
80 
5 
70 
6 and over 
65 
220.60 
Noncoincident Loads 
If two loads on the same feeder or service will not be operating simultaneously, the smaller of the two can be omitted for calculation purposes.
220.61 
Feeder or Service Neutral Load 
The feeder or service neutral load is by definition the maximum unbalanced load between the neutral and one ungrounded conductor. In threewire twophase or fivewire twophase systems the load is then multiplied by 140%. A factor of 70% is used in the case of household electric ranges, wallmounted ovens, electric dryers, and countermounted cooking units, when the maximum unbalanced load for ranges is in accordance with Table 220.55, and for dryers, Table 220.54. A factor of 70% may also be used for load more than 200 A in systems with threewire dc or singlephase ac; threephase, fourwire; twophase, threewire; and twophase, fivewire. Reduction of the neutral or the grounded conductor capacity of a 3 wire circuit with two phase wires and neutral of a fourwire wyeconnected threephase system is not permitted. Reduction of the neutral or grounded conductor capacity is also not permitted in a portion consisting of nonlinear loads on a 3phase, 4wire, wyeconnected system.
IV. Optional Feeder and Service Load Calculations
220.80 
General 
An optional calculation for feeder and service loads is permitted in accordance with this part (Part IV).
220.82 
Dwelling Unit 
(A) Feeder and Service Load. This section can be used to calculate the load for a single threewire, 120/240V or 208Y/120V feeder or service entrance with an ampacity of 100 A or larger. The neutral load can then be determined by Section 220.61. The load is the sum of (B) and (C) as follows:
(B) General Loads. These shall not be less than 100 percent of the first 10 kVA plus 40% of the remainder of the load listed as follows: each laundry and 20A small appliance circuit at 1500 VA, for general lighting and receptacles use 33 VA per sq. m or 3 VA per sq. ft., the nameplate rating of all fastened in place appliances, all motors and low power factor loads use the nameplate ratings.
(C) Heating and Air Conditioning Load. Use the largest of the following.
1. 100% of the nameplate rating(s) of the air conditioning and cooling.
2. 100% of the nameplate ratings of the heating when a heat pump is used without supplemental heating.
3. 100% of the nameplate ratings of electric thermal storage and other heating systems where the usual load is expected to be continuous at the full nameplate value. Systems qualify under this selection shall not be figured under any other selection in (c).
4. 100% of the nameplate rating of the heat pump compressor and 65% of the supplemental electric for central electric space heating systems. If the heat pump compressor cannot operate at the same time as the supplemental heat, then it does not have to be added to supplemental heat for the total central space heating load.
5. 65% of the nameplate rating(s) of electric space heating if less than four separately controlled units.
6. 40% of the nameplate rating(s) of electric space heating of four or more separately controlled units.
220.83 
Existing Dwelling Unit 
This section applies only to existing 120/240V and 120/208YV threewire services. It gives an alternate means of calculating loads. Refer to the section in the Code.
220.84 
Multifamily Dwelling 
This section permits an alternate means of calculation of feeder and service loads when each dwelling is supplied by a maximum of one feeder, has electric cooking, and has electric space heating or air conditioning. The alternate calculation is based on the demand factors shown in Table 220.84. These demand factors apply to the smallappliance branchcircuit load, 33 VA per sq. m or 3 VA per square foot general load, the nameplate rating of all appliances and motors, and the larger of the airconditioning or space heating loads. House loads are calculated in accordance with Part III of this article and are in addition to the dwelling unit loads calculated by Table 220.84. There is a listing of the connected loads which apply to the table.
Number of Dwelling Units 
Demand Factor (Percent) 

35 
45 
67 
44 
810 
43 
11 
42 
1213 
41 
1415 
40 
1617 
39 
1820 
38 
21 
37 
2223 
36 
2425 
35 
2627 
34 
2830 
33 
31 
32 
3233 
31 
3436 
30 
3738 
29 
3942 
28 
4345 
27 
4650 
26 
5155 
25 
5661 
24 
62 and over 
23 
220.85 
Two Dwelling Units 
220.86 
Schools 
Refer to Table 220.86.
Connected Load 
Demand Factor (Percent) 


First 33 VA/m2 Plus, 
(3 VA/ft2) at 
100 
Over 33 to 220 VA/m2 Plus, 
(3 to 20 VA/ft2) at 
75 
Remainder over 200 VA/m2 
(20 VA/ft2) at 
25 
220.87 
Determining Existing Loads 
Actual demand data can be used if the maximum readings are known for at least 1 year, the existing demand multiplied by 125% and the new loads are not larger than the wire capacity, and proper feeder and service overcurrent protection are provided, in accordance with Sections 240.4 and 230.90, respectively. There is an exception if the maximum demand is not available for 1 year.
220.88 
New Restaurants 
Table 220.88 can be used to calculate a service load or a feeder for a new restaurant if the feeder serves the total load. The serviceentrance overload protection must be in accordance with Sections 230.90 and 240.4. The feeder conductors do not have to be larger than the serviceentrance conductors. If this optional calculation is used, the neutral load of service or feeder conductors is determined by Section 220.61.
V. Farm Load Calculations
220.100 
General 
220.102 
Farm LoadsBuildings and Other Loads 
220.103 
Farm LoadsTotal 
Note: Examples for the calculations referred to in Article 220 are shown in Annex D of the NEC®. They are shown in the same location in this book for correlation.
Article 90 Introduction
General
Wiring and Protection
Wiring Methods and Materials
Equipment for General Use
Special Occupancies
Special Equipment
Special Conditions
Tables
Annex C. Conduit and Tubing Fill Tables for Conductors and Fixture Wires of the Same Size
Annex D. Examples
Annex E. Types of Construction