Circuit Breaker Selector
Choosing the right circuit breaker size ensures both equipment protection and electrical safety.
The Circuit Breaker Selector helps you determine the correct breaker rating based on load current, supply voltage, and safety factor, making it ideal for electrical engineers, panel designers, and technicians involved in residential, commercial, or industrial installations.
Electrical Breaker Size Calculator
Enter load power (kW), supply voltage, and power factor (default is 0.9).
Choose Single Phase or Three Phase.
Click Calculate Breaker Size.
The calculator instantly suggests:
Calculated load current
Recommended circuit breaker rating with safety margin
🧭 How to Use
FAQ
Q1. Why is correct breaker selection important?
A. Using an undersized breaker can cause nuisance tripping, while an oversized one may fail to protect cables or devices from overcurrent.
Q2. What is the safety margin for breaker selection?
A. Typically, a 25% margin is added to the calculated current to ensure reliability under surge or overload conditions.
Q3. Can I use this calculator for both single-phase and three-phase loads?
A. Yes, simply select your phase type from the dropdown menu — the calculator automatically adjusts the formula.
Q4. What if my required rating isn’t listed?
A. Choose the next higher standard breaker size or consult the manufacturer’s chart for a custom rating.