The Schneider Electric A9K14120 is a 1-pole miniature circuit breaker from the Acti9 iK60N range, rated 20 A at 30 °C with a C-curve trip characteristic (magnetic trip between 5 and 10 times In). It clips onto a standard DIN rail — two 9 mm pitches wide, so it takes up 18 mm of panel space. The breaking capacity is 4500 A Icn at 230 V AC, 50/60 Hz, certified to EN/IEC 60898-1.
The C-curve means the magnetic trip fires between 5 and 10 times the rated current — so for this 20 A breaker, instantaneous trip happens between 100 A and 200 A. If you were protecting a motor or a transformer with a higher starting surge, you'd typically reach for a D-curve instead. The thermal-magnetic trip unit handles the overload side (the thermal bimetal) and the short-circuit side (the magnetic coil) in one compact package. Rated insulation voltage is 440 V AC, and the overvoltage category is III, which covers fixed installations inside a building distribution board. The part is rated for isolation — it has a positive ON/OFF indication on the toggle, so you can visibly confirm the circuit is open before working downstream.
Termination and wiring notes
Strip length is 14 mm.