The rated voltage of the circuit breaker is RMS Phase to Phase Voltage.
The rated voltage of a circuit breaker refers to the maximum voltage that the breaker is designed to operate at.
This voltage rating may be expressed in different ways depending on the specific application, such as RMS phase-to-phase voltage, RMS phase-to-ground voltage, or peak voltage.
For example, in a three-phase power system, the rated voltage of a circuit breaker may be expressed as the RMS phase-to-phase voltage, which is the voltage measured between any two of the three phases. This voltage rating indicates the maximum voltage that the circuit breaker can safely interrupt without suffering damage or failure.