Electrical Load Calculation

How it works

For electricians checking whether an existing home's service can handle an EV charger, a heat pump, a hot tub or a shop. Enter the square feet and the service size, and list the fixed appliances and equipment the way you'd read them off the nameplates (“range 12 kW, dryer 5,500 W, water heater 4,500 W, 3 ton heat pump 28 A at 240, new EV charger 48 A”). Electrical Load Calculation works it out by the NEC 220.83 optional method for an existing dwelling: 3 VA per square foot for lighting and receptacles, 1,500 VA for each small appliance and laundry circuit, every fixed appliance at its nameplate rating, the first 8,000 VA at 100% and the rest at 40%, plus heating and air conditioning at 100%. You get a clean worksheet showing every line, the total in VA and amps at 240 volts, and how it compares to the service. Ratings that aren't given are listed instead of guessed. A licensed electrician should confirm before a service change.

NEC 220.83 optional method. Check the code edition your inspector uses; a licensed electrician should confirm it.