What this MCB does on the panel
The Schneider Electric A9KF21216BQ is a 2-pole miniature circuit breaker from the Acti9 K60 family, rated 16 A with a B-curve trip characteristic (magnetic tripping between 3 and 5 times In). It protects final circuits against overload and short-circuit in AC distribution boards, with a breaking capacity of 10 kA Icn at 415 V AC 50/60 Hz, certified to EN/IEC 60898-1. The 36 mm width (4 x 9 mm pitches) snaps onto a DIN rail, and the tunnel terminals accept up to 25 mm² rigid or 16 mm² flexible cable — sized for the incoming feed on a lighting or socket-outlet subcircuit.
B-curve selectivity and coordination
The B-curve (3–5 x In) means the magnetic trip initiates at 48–80 A instantaneous. That is deliberately higher than a C-curve's 5–10 x In, so this breaker coordinates better with upstream devices on a residential or light-commercial panel where downstream cable runs are short and inrush from incandescent or resistive loads is low.
Fixed DIN-rail mount, 36 mm wide (4 module pitches). The toggle control gives clear visual indication of the contact position.