Minimum demand load is whatever is greater, 5000W or nameplate data
Apply table 220.54 (pg 70-73) if ≥ 5 dryers
kVA is equivalent to kW for dryers
Step 04: Cooking Equipment
220.55 chart/table
Note 4: Permissible to use table 220.55-note 4 to calculate branch-circuit load sizing for 1 range
Branch-circuit load sizing for 1 wall-mounted oven or 1 counter-mounted cooking unit must be the appliance nameplate rating.
Branch-circuit load sizing for 1 counter-mounted cooking unit and 1 or 2 wall-mounted ovens is determined by adding nameplate ratings together & treating the resultant value as a single range.
Equipment rated over 1¾ kW calculated according to table 220.55 (pg 70-74)
Including Notes 1, 2, & 3 for determining demand loads
Demand Load = Column C Value * Multiplier
MH-pg 404, Table 220.55, Note 1
Step 05: Air-conditioning VS Heat
220.50
220.51
220.60
Air conditioning or heating load are calculated at 100%
If both not on at same time, smaller of 2 loads can be omitted
If both are on at same time, both are added together
Step 06: Feeder & Service Conductor Size
310.15(B)(7)(1) through (3)
Use this section to size the service & feeder conductors supplied by 1 Ø, 120/240V & 120/208V for a 1-family dwelling ^{&}/_{or} single unit of 2-family/multi-family dwelling and size Service conductors to 83% of service over-current protection device rating.
83% rule can not be used for service conductors of 2-family and muilti-family units.
DO EXAMPLE MH-PG 407
Optional Method, Steps to determine Feeder or Service size, single Dwelling Unit (Article 220, Part III)
Can only be used for dwelling units served by a single 120/240V or 120/208V, 3-wire set of service or feeder conductors with an ampacity of 100A or greater
220.82
Step 01: General Loads
220.82(B)
Demand Load
not less than 100% for the 1st 10 kVA, plus
40% of the remainder of the following:
General Lighting & Receptacles
3 VA per Sq. Ft
Small-appliance & Laundry
1500 VA for each 20A circuit specified in 220.52
Appliances
Nameplate VA rating of all permanent appliances & Motors
except haeting & Air-conditioning
Ensure range & dryer calculations use nameplate rating
Step 02: Largest of Air-Conditioning VS Heating
220.82(C)
Include the larger of (1) through (6)
Air-conditioning equipment
100%
Heat-pump compressor without Supplemental Heating
100%
Heat-pump compressor and Supplemental Heating
100% of heat-pump compressors nameplate rating and,
65% of supplemental electric heating for central electric space-heating
If heat-pump compressor is interlocked preventing simultaneous supplemental heat operation, omit it from calculation
Space-heating units
3 or fewer units
65%
Space-heating units
4 or more units
40%
Thermal Storage Heating
100%
Step 03: Service Size
310.15(B)(7)
310.15(B)(7)(1) through (4) can size 1Ø, 120/240V service & feeder conductors for 1-family dwellings & individual units of multiple unit 9dwellings
Existing Dwelling Unit Optional Load Calculations
220.83
Used to determine if existing service or feeder is sufficient capacity to serve additional loads using optional method
Existing installation feeder or service load calculations can also be based on maximum demand
220.87
Step 01: General Loads
220.83(B)
Demand Load
not less than 100% for the 1st 8 kVA, plus
40% of the remainder of the following:
General Lighting & Receptacles
3 VA per Sq. Ft
Small-appliance & Laundry
1500 VA for each 20A circuit specified in 220.52
Appliances
Nameplate VA rating of all permanent appliances & Motors
except haeting & Air-conditioning
Ensure range & dryer calculations use nameplate rating
Step 02: Largest Air-conditioning VS Heating
220.83(C)
Include the larger equipment
Step 03: Service Size
310.15(B)(7)
310.15(B)(7)(1) through (4) can size 1Ø, 120/240V service & feeder conductors for 1-family dwellings & individual units of multiple unit 9dwellings
Neutral Load Calculations
Cooking Equipment Neutral Load
220.61(B)(1)
Calculated at 70% of the demand load determined by 220.55
Dryer Neutral Load
220.61(B)(1)
Calculated at 70% of the demand load determined by 220.54
Neutral Amperes = Neutral Demand Load / System Voltage
Unit 10: Multi-Family Dwelling Calculations
NEC Article 220
NEC Example problems in Appendix, pg 70-791-799
2 different calculation methods
Standard
Optional
Standard Method, Steps to determine Feeder or Service size for a Dwelling Unit (Article 220, Part III)
Step 01: Determine feeder demand factor load for General Lighting, General-use Receptacles, Small appliances, and Laundry circuits (220.42)
Determine the total connected load (220.52)
General lighting & receptacles at 3 VA per sq ft (of interior floor plan)
220.12
2 Appliance circuits each at 1500 VA
220.52(A)
1 Laundry circuit at 1500 VA
220.52(B)
NEC requires a minimum of 3 VA per Sq Ft to determine branch circuit feeder & service calculations
Includes all 15A & 20A general-use receptacles
Does not include small appliances & laundry circuit receptacles
Apply table 220.42 (pg 70-72) demand factors to the total connected load
Calculate 1st 3000 VA at 100% and remaining VA at 35% demand
Step 02: Appliances
220.53
Apply 75% demand factor for four or more permanent appliances
Include all appliances in all dwelling units
Does not apply to electric loads in following steps below
Step 03: Clothes Dryer
220.54
Minimum demand load is whatever is greater, 5000W or nameplate data
Adjust according to table 220.54 (pg 70-73)
Dryers in common laundry rooms do not do load calculations using this method
Step 04: Cooking Equipment
220.55 chart/table
Equipment rated over 1¾ kW calculate feeder & services according to table 220.55 (pg 70-74)
Including Notes 1, 2, & 3 for determining demand loads
Note 1: Ranges rated more than 12 kW, the maximum demand in Column C is increased 5%for each kW, or major fraction, over 12kW
Note 2: Ranges of different ratings, use a minimum of 12 kW for ranges rated less than 12 kW and use average kW rating across all ranges to determine the column C demand load
1Ø Cooking equipment supplied by 3Ø , 4-wire Service
220.55
Total load is based on twice the maximum number of cooking equipment connected between any 2Ø