Circuit Breaker Selection Calculator

The circuit breaker protects the cable, not the load.

Circuit Breaker
Tripping Curve
Operating current Ib 20 A · 0×In
Status
—
Tripped by
—
Recommended rating — Minimum cross-section —
Circuit type
Nominal rating 25 A
Tripping curve
Voltage 230 V
Cross-section 4 mm²
The breaker is sized for the cable, not the load
Run length 20 m
Determines voltage drop and short-circuit current
Installation scenario —
Earthing system
RCD
Protective device
Installation method B2
Ambient temperature 25 °C · k₁ 1.00
Capacity increases below 30°C. Conservatively leave at 30°C
Circuits in bundle 1 · k₂ 1.00
Co-routed, simultaneously loaded circuits
Loaded cores
Thermal insulation k₃ 1.00
Earth fault loop impedance Ze
Ω
Earth resistance RA
Ω
RA × IΔn ≤ 50 V
Required disconnection time
Disconnection current Ia
A
Manufacturer's curve
Voltage drop limit
Power factor cos φ 1.00
Breaking capacity Icn
Reduced PE conductor
Design summary

Scope of validity

Reference calculation only.

Calculation method.

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