Panel Load Calculator
NEC Article 220. Add circuit loads, apply demand factors, and determine if a panel upgrade is needed.
Panel Load (NEC 220)
Circuits / Loads
What is a panel load calculation?
A panel load calculation totals all the electrical loads in a building to determine whether the existing service and panel can handle them — and what size panel is needed for new or expanded service.
NEC demand factors (Article 220)
NEC allows demand factors to be applied because not all loads run simultaneously. This calculator applies the NEC optional calculation method:
- First 10,000W at 100%
- Remaining load at 40%
- Continuous loads (3+ hours) calculated at 125%
Standard panel sizes
- 60A
- 100A
- 125A
- 150A
- 200A
- 225A
- 320A
- 400A
200A is the most common residential service. 400A for large homes or light commercial.
80% rule
A panel is considered at capacity when loads reach 80% of its rating. Above 80%, a panel upgrade is typically recommended even if technically within limits — this is the NEC 230.42 continuous load rule applied to service equipment.
Quote panel upgrades faster with CircuitDesk
Run the load calculation, then build the quote and invoice right in CircuitDesk. No spreadsheets, no back-and-forth — everything from estimate to payment in one place.