NEC-Electrician: Residential Load Calculation Basics — Flashcards

Residential (dwelling unit) load calculation estimates the electrical demand so service/feeder sizes are adequate. Key idea: you don’t add every nameplate at 100%—the NEC applies demand factors because not everything runs at once. In exam terms you’ll see: general lighting load, small-appliance circuits, laundry circuit, fixed appliances, HVAC vs heat (largest), and optional methods for dwellings.

Worked example 1 (simple general load concept):
Dwelling general lighting load is often based on square footage (value comes from NEC). Add required small-appliance and laundry loads. Then apply applicable demand factors (per method used).
Worked example 2 (HVAC vs heat):
If you have a 5 kW electric furnace and a 3 kW AC, you generally count the larger (5 kW), not both together (unless the system can run simultaneously by design).