Circuit Breaker Size Calculator
Calculate the correct circuit breaker amperage for electrical circuits
About this calculator
The Circuit Breaker Size Calculator helps determine the appropriate amperage rating for circuit breakers based on your electrical load requirements. This tool ensures electrical safety by calculating the correct breaker size to protect circuits from overcurrent conditions while preventing nuisance tripping. Proper circuit breaker sizing is essential for code compliance, fire prevention, and protecting electrical equipment and wiring from damage caused by electrical overloads.
How to use
Enter your total electrical load in watts or amps, select your voltage (120V, 240V, etc.), and specify the circuit type. The calculator will determine the minimum required breaker amperage and recommend the next standard breaker size. Always verify calculations meet local electrical codes and consult a licensed electrician for installation.
Frequently asked questions
What's the 80% rule for circuit breakers?
Circuit breakers should only be loaded to 80% of their rated capacity for continuous loads to prevent overheating and ensure safe operation.
Can I use a larger circuit breaker than calculated?
No, oversized breakers won't properly protect the wire and can create fire hazards. Use the calculated size or consult an electrician.
What's the difference between 15A and 20A breakers?
15A breakers protect circuits up to 12 amps continuous load, while 20A breakers handle up to 16 amps continuous load safely.