Electrical Load Calculator

Calculate residential electrical panel load and service size using NEC demand factor method for general lighting, appliances, and major loads.

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What This Calculator Does

Calculate residential electrical panel load and service size using NEC demand factor method for general lighting, appliances, and major loads.

It combines Home Square Footage (3 VA/sqft), Small Appliance Circuits (1500W each), Laundry Circuits (1500W each), Range/Oven (Watts) to estimate Total Demand Load, Calculated Service Amps, Recommended Service Size.

Formula & Method

General load is VA_g=3\cdot Area+1500\cdot Circuits_{small}+1500\cdot Circuits_{laundry}. NEC demand applied as VA_{demand}=3000+0.35(VA_g-3000) for VA_g>3000. Total demand adds major appliance/HVAC loads, then service current I=\frac{VA_{total}}{240}.

Notation used in the formulas: R = Total Demand Load; x_{1} = Home Square Footage (3 VA/sqft); x_{2} = Small Appliance Circuits (1500W each); x_{3} = Laundry Circuits (1500W each); x_{4} = Range/Oven (Watts); x_{5} = Dryer (Watts); x_{6} = Air Conditioning (Watts).

Method summary: inputs are normalized to consistent units, core equations are evaluated, then secondary values are derived and rounded for display.

Use this calculator for quick scenario analysis. Start with baseline values, change one driver at a time, and compare how sensitive the results are to each input shown above.

Inputs Used

Home Square Footage (3 VA/sqft): Used directly in the calculation.
Small Appliance Circuits (1500W each): Used directly in the calculation.
Laundry Circuits (1500W each): Used directly in the calculation.
Range/Oven (Watts): Used directly in the calculation.
Dryer (Watts): Used directly in the calculation.
Air Conditioning (Watts): Used directly in the calculation.
Water Heater (Watts): Used directly in the calculation.
Other Loads (Watts): Used directly in the calculation.

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