It protects a 1P+N final circuit against overload, short-circuit, and earth leakage, with a 30 mA sensitivity that covers personnel protection (additional protection against direct contact) and fire prevention in TN earthing systems.
For most domestic and small commercial installations in the UK and Europe, this is sufficient — but if your upstream fault level exceeds 10 kA (e.g., close to a transformer), you need a higher-rated device or a current-limiting upstream MCB. The 30 mA earth-leakage threshold is the standard for additional protection per BS 7671 (18th Edition) — it catches fault currents that could otherwise cause ventricular fibrillation. The thermal-magnetic trip unit handles the overcurrent side; the integrated residual current module handles the leakage side. Both share the same compact 18 mm footprint, so it replaces a separate MCB + RCCD combination in a single DIN-rail slot. IP20 rated — install inside an enclosure, not in washdown areas.