When sourcing MCBs, you must prioritize the Rated Breaking Capacity (Icn), typically ranging from 6kA to 10kA for standard applications, to ensure the device can interrupt fault currents without damage. Additionally, verify the Tripping Characteristics (Curves B, C, or D): Curve B is for resistive loads, Curve C for general commercial/industrial use, and Curve D for high inductive loads like motors. Ensure the Rated Current (In) and Rated Voltage (Ue) align perfectly with your local grid requirements.