How do I calculate the correct circuit breaker rating for a home EV charger installation?

To correctly size a circuit breaker for a residential EV charger, apply the IEC 61851-1 standard which classifies charging modes and requires continuous load consideration. Calculate the design current by dividing the charger’s maximum power rating (e.g., 7.4 kW for a single-phase 32 A unit) by the nominal voltage (230 V), yielding 32.17 A. Per IEC 60364-5-52, a circuit breaker rated at 40 A with a Type B or C tripping curve is typically selected after applying a 125% factor for continuous loads as specified in many national codes derived from these standards, ensuring the protective device does not exceed 80% of its rating under sustained operation.