Overview
The residential load calculator determines the total electrical demand for a dwelling unit using the NEC optional calculation method (Section 220.82 in NEC 2023 / Section 120.82 in NEC 2026). This is the method most electricians use for residential service sizing.
The calculator supports both the NEC 2023 and 2026 methods, automatically adjusting the general lighting load (3 VA/sq ft vs. 2 VA/sq ft) and article references based on the selected edition.
Load Categories
The optional method includes these load categories:
- General lighting: Square footage × VA/sq ft (3 VA for NEC 2023, 2 VA for NEC 2026)
- Small appliance circuits: 1,500 VA per circuit (minimum 2 per NEC 210.11(C)(1))
- Laundry circuit: 1,500 VA per NEC 210.11(C)(2)
- Fixed appliances: Nameplate VA (water heater, dishwasher, disposal, etc.)
- Range/oven: Demand factors per Table 220.55/120.55 based on kW rating
- Dryer: Demand factors per Table 220.54/120.54
- HVAC: Larger of heating or cooling (non-coincident per 220.60/120.60)
- EV charger: Typically 7,680 VA (240V, 32A Level 2) at 100% demand factor
Optional Method Calculation
The optional method applies a simplified demand factor:
- Sum all loads (general lighting + small appliance + laundry + all fixed loads)
- First threshold at 100% (8,000 VA for NEC 2026, 10,000 VA for NEC 2023)
- Remainder at 40%
- Add HVAC and EV at 100%
- Total = calculated demand in VA
- Service amps = Total VA / (240V for single-phase)
The output recommends a standard service size: 100A, 150A, 200A, 300A, or 400A.
NEC References
- NEC 220.82/120.82 — optional method for dwelling unit calculations
- NEC 220.83/120.83 — optional method for existing dwelling units
- NEC 120.87 — removed load credit (new in 2026 NEC)
- NEC Table 220.42/120.42 — lighting demand factors
- NEC Table 220.54/120.54 — dryer demand factors
- NEC Table 220.55/120.55 — range/oven demand factors
- NEC 220.60/120.60 — non-coincident load rules (heating vs. cooling)
Try it yourself
Calculate voltage drop for single-phase and three-phase circuits per NEC 2026 standards.
Calculate residential service size per NEC 2026 optional method with demand factor breakdown.
Calculate wire size per NEC Table 310.16 with temperature and conduit fill derating.
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