Demand Load Calculator
Calculate residential service demand load per NEC Article 220: general lighting, appliances, HVAC, and service size.
Inputs
NEC Table 220.12: 3 VA/ft² for dwellings; demand factors per NEC Table 220.42
NEC 210.11(C)(1): minimum 2 kitchen small appliance circuits × 1,500 VA = 3,000 VA
NEC 220.51: electric heating at 65% demand; NEC 220.60: count only larger of AC vs. heat
Results
Calculated Demand Load
24,785 VA
Minimum Service Size
125 A
How to Use This Calculator
- Enter the Floor Area in m² — NEC Article 220 assigns 33 VA/m² for general lighting in dwellings.
- Enter the number of Kitchen Small Appliance Circuits (NEC minimum is 2) and Laundry Circuits (minimum 1).
- Enter the total Fixed Appliance Loads in VA — sum nameplate VA for range, dryer, dishwasher, and water heater.
- Enter the Air Conditioning Load and Electric Heating Load in VA — NEC uses the larger of the two with a 65% demand factor on heating.
- Enter the EV Charger Load in VA if applicable (e.g., Level 2 at 240V × 30A = 7,200 VA) — counted at 100% demand.
- Read the Calculated Demand Load in VA and the Minimum Service Size in amperes to select the correct service entrance equipment.
How the result changes with EV Charger Load
| EV Charger Load | Calculated Demand Load | Minimum Service Size |
|---|---|---|
| 2,000 | 19,585 VA | 100 A |
| 7,000 | 24,585 VA | 125 A |
| 13,000 | 30,585 VA | 150 A |
| 18,000 | 35,585 VA | 150 A |
What each input means
- Floor Area
- Total floor area of the dwelling in square meters. NEC Table 220.12 requires 3 VA/ft² (33 VA/m²) for general lighting in dwelling units. First 3,000 VA at 100%, remainder at 35% demand factor.
- Kitchen Small Appliance Circuits
- Number of 20A kitchen small appliance circuits. NEC 210.11(C)(1) requires a minimum of two 20A small appliance branch circuits for kitchen receptacles. Each 20A circuit = 1,500 VA.
- Laundry Circuits
- Number of laundry circuits (at least 1 required per NEC 210.11).
- Fixed Appliance Loads
- Total nameplate VA of fixed appliances (range, dryer, dishwasher, water heater, etc.).
- Air Conditioning Load
- Total air conditioning nameplate VA. Used if larger than heating.
- Electric Heating Load
- Total electric heating nameplate VA. NEC 220.51 permits 65% demand factor for electric heating loads. Only the larger of AC or heating is counted in demand calculations per NEC 220.60.
- EV Charger Load
- EV charger nameplate VA (e.g., Level 2 at 240V × 30A = 7200 VA). 100% demand.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersFloor Area = 200, Kitchen Small Appliance Circuits = 2, Laundry Circuits = 1, Fixed Appliance Loads = 9000 = 7 input(s) provided
- Calculate Calculated Demand LoadCalculated Demand Load24785 = 24785
- Calculate Minimum Service SizeMinimum Service Size125 = 125
- Calculate General Lighting LoadGeneral Lighting Load6600 = 6600
- Calculate Small Appliance + Laundry4500 = 4500
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