The Schneider Electric A9N16256 is an Acti9 xID residual current circuit breaker (RCCB) — a 4-pole, 40 A device with 300 mA earth-leakage sensitivity, Type AC, rated for 400-415 V AC at 50 Hz. This is the part you spec into a distribution board when you need basic sinusoidal AC fault protection on a three-phase circuit with neutral. It is not for personnel protection — that calls for 30 mA or lower.
The 4-pole body takes 8 module pitches at 18 mm per phase — 144 mm of rail width total. Tunnel-type terminals top and bottom accept 1 to 35 mm² rigid or 1 to 25 mm² flexible cable; strip 14 mm and torque to 3.5 N·m. Neutral is on the left. The toggle gives local ON/OFF/fault-trip indication, and there is a padlocking provision for lockout/tagout. IP20 rated — clean, dry indoor panel only, no washdown.
Current production. This is not an obsolete or NRND line — the Acti9 xID range is Schneider's standard RCCB family for European and export markets. The part carries EN/IEC 61008-1 and EN/IEC 61008-2-1 certification, so it is accepted across most jurisdictions that adopt IEC standards. Same part, different passport — a genuine unit regardless of which authorized region it was sourced from.