Enter your home's Total Living Area, Appliance Circuits, Laundry Circuits, and major loads like Range, Dryer, and HVAC Units into the Demand Factor Calculator to find your Total Demand Load, General Load Demand, Appliance Load, and Recommended Service Size.
Total Demand Load
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General Load
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General Load Demand
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Appliance Load
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Recommended Service Size
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A demand factor is a multiplier applied to electrical loads to account for the fact that not all loads operate simultaneously at full capacity. It helps determine the actual electrical demand rather than the connected load.
General load is calculated at 3VA per square foot of living area, plus 1500VA for each small appliance circuit (minimum 2), plus 1500VA for each laundry circuit, according to NEC requirements.
The first 3000VA is at 100%, the next 117,000VA (3001-120,000VA) is at 35%, and any amount over 120,000VA is at 25%, per NEC Table 220.42.
Major appliances like ranges, dryers, and ovens have specific demand factors. Electric ranges use NEC Table 220.55, while other appliances are typically calculated at 100% of their nameplate rating.
The service ampacity should be at least 100A for residential properties. Common sizes are 100A, 125A, 150A, and 200A. Choose the next standard size above your calculated demand load divided by 240V.
HVAC loads are typically included at 100% of their nameplate rating, but only the larger of heating or air conditioning is counted since they don't operate simultaneously.
Adding all connected loads would result in oversized electrical services. Demand factors account for diversity in load usage - not all electrical devices operate at maximum capacity simultaneously.