Circuit Breaker Sizing Calculator
Calculate the correct breaker size for a circuit based on connected load, voltage, and NEC safety factor.
W
Recommended Breaker
25 A
Actual Current Draw20.0 A
Design Current25.0 A
Recommended Breaker vs Total Connected Load
Formule
## Circuit Breaker Sizing **Amps = Watts / Volts** **Continuous load: multiply by 1.25** per NEC 210.20(A). Then round up to the next standard breaker size (15A, 20A, 30A, 40A, 50A, etc.).
Exemple Résolu
2,400W continuous load on 120V.
- 01Amps = 2400 / 120 = 20A
- 02Design amps = 20 x 1.25 = 25A
- 03Next standard size = 25A, or use 30A breaker
Questions Fréquentes
What makes a load continuous?
A continuous load operates for 3 hours or more without interruption. Examples include lighting, electric heaters, and HVAC equipment.
Can I use the full breaker rating for non-continuous loads?
Yes, non-continuous loads can use up to 100% of the breaker rating. However, mixed circuits with both continuous and non-continuous loads must account for each portion separately.
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