--- Skip to content
🔌

Circuit Breaker Selector

This calculator selects the rating and characteristic of a circuit breaker based on load type and power. Calculation per IEC 60898 and GOST R 50571. All computation is client-side.

Leave 0 to calculate from power

How the selection works

1. Calculated current: I = P / (U × cos φ) for single-phase, I = P / (√3 × U × cos φ) for three-phase.
2. Breaker rating — next standard value from the series: 6, 10, 16, 20, 25, 32, 40, 50, 63 A.
3. Characteristic: B — for lighting/sockets (instant trip 3–5×In), C — for motors/AC (5–10×In).
4. Cable cross-section — per IEC ampacity table.