Circuit Breaker Sizing
Calculator

Inputs

Breaker rating (A)
20

Results

Breaker rating (A)
20

Electrical results

Breaker rating (A)20

formula-map diagram

Breaker rating (A)
20

Electrical relationship

Formula

I_breaker = I_load × safety factor

= 20

Note

This is a simplified model: it applies the textbook relationship to the numbers you entered and assumes ideal components, steady-state sinusoidal conditions, balanced loads and copper resistivity of 0.0172 Ω·mm²/m at 20 °C. It ignores component tolerances, temperature drift, skin effect, harmonics, inrush, transformer and battery losses, and it is not a substitute for the wiring code that applies where you are. Have any installation sized and verified by a licensed electrician or engineer.

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