Electrical
Electrical Load Calculator
Estimate a dwelling's electrical load and the service size it points to, using the NEC standard method.
Result
Electrical work is life-safety work governed by the NEC or your local code, and must be designed and installed by a licensed electrician. Conductor and overcurrent sizing depends on ambient temperature, conductor bundling, termination ratings, continuous-load rules and more. This is an educational estimate and must never be used as the basis for an installation. This follows the shape of the NEC Article 220 standard method but simplifies it considerably: range demand factors, dryer minimums, largest-motor rules and the optional calculation method all change the result. A licensed electrician must perform the actual load calculation.
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About this calculator
Do I need a 200 amp service?
Most modern homes with electric cooking, electric drying and central air land on 200 A. Adding EV charging or a heat pump frequently pushes older 100 A services past their limit.
Why are lighting loads derated?
Because not everything runs at once. The NEC applies demand factors reflecting realistic simultaneous use rather than the sum of every connected load.
The formula
general lighting = 3 VA per sq ft; first 3,000 VA at 100%, remainder at 35%; plus appliance and HVAC loads
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