Input Parameters
About This Calculator
- NEC 220 standard method
- First 10kVA @ 100%, rest @ 40%
- HVAC: max(heat, cool)
How this electrical load calculator works
NEC 220 standard method: lighting at 33 VA/m², required circuits, fixed appliances at nameplate. Demand factor: first 10kVA at 100%, remainder at 40%.
HVAC uses the larger of heating or cooling. Service amps = demand VA / 240V.
FAQ
Residential load calc?
NEC 220: lighting + circuits + appliances + HVAC.
Service size needed?
Most homes: 200A. Large: 300-400A.
Demand factor?
First 10kVA×100% + rest×40%.