The Schneider Electric A9N16259 is a 4-pole residual current circuit breaker (RCCB) from the Acti9 xID family, rated 63 A with 100 mA earth-leakage sensitivity. Rated operational voltage is 400...415 V AC at 50 Hz, with a breaking and making capacity of 630 A conforming to EN/IEC 61008-1.
The 100 mA sensitivity is less sensitive than the 30 mA version — it's sized for circuits where nuisance tripping from cable charging currents or equipment leakage is a concern, but where the fault path still needs to be interrupted before a sustained earth fault becomes a shock hazard. Type AC is the most common RCCB type; it will trip on sinusoidal AC residual currents but not on pulsed DC or smooth DC from rectifiers or VFDs. If the downstream loads include switched-mode power supplies or variable-speed drives, a Type A or Type F RCCB would be required instead. The 4-pole construction (4P) with neutral on the left covers three-phase plus neutral circuits. Insulation voltage is rated at 500 V AC, so the part is suitable for 400 V systems with headroom. The instantaneous trip time (no intentional delay) means it clears earth faults as fast as the internal mechanism allows — important for personnel protection in circuits where coordination with downstream RCBOs isn't required. Mounting is clip-on to DIN rail, occupying 8 x 9 mm pitches (72 mm wide). The tunnel-type terminals accept 1...35 mm² rigid or 1...25 mm² flexible cable, with a tightening torque of 3.5 N.m.
The part is suitable for isolation (disconnector function) and carries a contact position indicator showing ON, OFF, or fault trip status.