Home Occupancy Load Calculator
Estimate the total electrical occupancy load for a residential home using the NEC (National Electrical Code) general lighting load method plus major appliance loads.
NEC minimum is 2 circuits (1500 VA each)
NEC minimum is 1 circuit (1500 VA each)
Formula & Method
This calculator uses the NEC Article 220 Standard Method for residential load calculations:
- General Lighting Load: Floor Area (sq ft) × 3 VA/sq ft (NEC 220.12)
- Small Appliance Circuits: Number of Circuits × 1,500 VA (NEC 220.52(A), minimum 2)
- Laundry Circuit(s): Number of Circuits × 1,500 VA (NEC 220.52(B), minimum 1)
- Demand Factors applied to subtotal (NEC Table 220.42):
- First 3,000 VA → 100%
- 3,001 VA to 120,000 VA → 35%
- Over 120,000 VA → 25%
- Electric Range: Single range ≤12 kW = 8,000 W demand; >12 kW add 400 W per kW above 12 kW (NEC Table 220.55, Column C)
- Electric Dryer: max(nameplate, 5,000 W) (NEC 220.54)
- HVAC: Larger of AC or Heat load (non-coincident) (NEC 220.60)
- Water Heater: 100% of nameplate rating
- Service Amps: Total VA ÷ Voltage
Assumptions & References
- Calculations follow NFPA 70: National Electrical Code (NEC) 2023, Article 220 — Branch-Circuit, Feeder, and Service Load Calculations.
- Standard method is used (not the optional method of NEC 220.82–220.87).
- Power factor is assumed to be 1.0 (unity) for resistive loads; VA = Watts.
- Non-coincident loads (AC vs. Heat): only the larger load is counted per NEC 220.60.
- Minimum 2 small appliance circuits and 1 laundry circuit are required by NEC regardless of actual count.
- Range demand uses NEC Table 220.55 Column C for a single household cooking appliance.
- Recommended service sizes follow standard residential panel ratings: 100, 125, 150, 200, 225, 300, 400 A.
- This calculator provides an estimate only. A licensed electrician should verify all load calculations before installation.
- Does not include EV charger loads, solar/battery systems, or commercial kitchen equipment.