When sourcing RCCBs, you must prioritize the Type (AC, A, B, or S) based on the load. Type AC is for standard resistive loads, while Type A and B are essential for circuits with electronic components or EV charging. Ensure the Rated Current (In) matches your circuit (e.g., 25A, 40A, 63A) and the Rated Residual Operating Current (IΔn) is typically 30mA for personnel protection or 100mA/300mA for fire protection. Additionally, verify the Short-circuit breaking capacity (Inc), which should ideally be 6kA or 10kA for robust industrial applications.