The A9N18390 is a 4-pole Acti9 C120N miniature circuit breaker rated 63 A at 30 °C with a D tripping curve (10–14 × In magnetic trip). Breaking capacity is 10 kA Icn at 400 V AC per EN/IEC 60898-1, and 6 kA Icu at 440 V AC per EN/IEC 60947-2. For DC circuits it's rated 10 kA Icu at ≤500 V DC, so it works on 480 V DC bus applications too. Dual-rated to EN/IEC 60898-1 and EN/IEC 60947-2, which means it qualifies both as a domestic MCB and as an industrial circuit breaker for isolation duty (suitability for isolation confirmed per IEC 60947-2).
At 108 mm wide (12 × 9 mm pitches) for 4 poles, it occupies the expected 4-module width in a distribution board. Tunnel terminals accept 1–50 mm² rigid or 1.5–35 mm² flexible, with a 3.5 N·m tightening torque and 15 mm strip length — standard for panel wiring with no surprises. IP20 finger protection on the front, so it's safe for open-panel mounting but not for washdown areas.