Home Wiring Load Calculator

Calculating Your Home's Electrical Load

Before adding new circuits, a home rewire, or sizing a solar or generator system, you need to calculate your total electrical load. This prevents overloaded circuits, tripped breakers, and fire hazards.

Load Calculation Method (NEC-Based)

The National Electrical Code (NEC) specifies a standard method:

1. General lighting load: 3 VA per sq ft (33 VA per m²) of floor area.
2. Small appliance circuits: 1,500 VA per circuit (minimum two required in kitchen).
3. Fixed appliances: Nameplate watts for HVAC, water heater, dryer, range, etc.
4. Apply demand factors: The first 10,000 VA at 100%, remainder at 40%.

Total Amps = Total VA / Supply Voltage

How to Use This Calculator

Enter each load — appliance, rated power, and number of units. The calculator totals the load, applies demand factors, and recommends main breaker and service entrance sizes.

Practical Examples

Example — 2,000 sq ft home:

• Lighting: 2,000 × 3 = 6,000 VA
• Kitchen circuits: 2 × 1,500 = 3,000 VA
• Dryer: 5,500 VA; Range: 12,000 VA; AC: 5,000 VA; Water heater: 4,500 VA
• Total: 36,000 VA; After demand factor: ~22,000 VA
• Service: 22,000 / 240 = 92A → 100A service minimum (200A recommended for EV charging, additions).