Electrical Load Calculator
Determining total electrical load is necessary for sizing service entrance equipment, panel upgrades, and evaluating whether existing service can handle additional circuits. This calculator follows NEC Article 220 standard load calculation methods for residential dwelling units.
Residential Service Load Calculator
Based on NEC Article 220 standard method. Actual service sizing must account for demand factors, future expansion, and local code requirements. Consult a licensed electrician for panel upgrade decisions.
Standard Residential Service Sizes
| Service Size | Typical Home | Common Applications |
|---|---|---|
| 100A | Small home, gas appliances | Older homes, minimal electric load |
| 150A | Medium home, some electric | Standard for many older subdivisions |
| 200A | Standard modern home | Current minimum code for new construction |
| 320A | Large home, all-electric | EV charger + electric HVAC + pool |
| 400A | Large estate or dual panels | Multiple HVAC zones, shop, pool house |
Frequently Asked Questions
How do I know if I need a panel upgrade?
Common signs include: frequently tripping breakers, no available breaker slots for new circuits, planning to add an EV charger or HVAC system, or having a service panel rated below 200A in a home with significant electric loads. A load calculation determines whether your existing service can handle additional loads.
What is the NEC demand factor?
Demand factor recognizes that not all loads run simultaneously. For general lighting and receptacles, the first 3,000 watts are counted at 100%, and the remainder at 35%. This prevents oversizing service entrance equipment based on the unlikely scenario that every circuit draws maximum current at the same time.