The ABB 2CSF204005R1800 is a four‑pole residual current circuit breaker (RCCB) from ABB’s F200 series, designed to detect and interrupt earth leakage (ground fault) currents to protect people and electrical installations. It continuously monitors the difference between phase and neutral currents and trips the circuit if residual (leakage) current exceeds a set threshold, helping prevent electric shock and fire hazards. This product conforms to international IEC safety standards and is suitable for low‑voltage AC power systems such as residential, commercial, and light industrial distribution boards.