Acti9 iC60H miniature circuit breaker, 25 A, D curve
The Schneider Electric A9F08125 is a 1-pole Acti9 iC60H miniature circuit breaker rated at 25 A with a D tripping curve, designed for distribution applications where high inrush currents — typical of motor, transformer, or lighting loads — require a magnetic trip threshold of 12 x In (±20 %) to avoid nuisance tripping. Its breaking capacity reaches 42 kA Icu at 12–60 V AC and 15 kA Icu at 220–240 V AC per EN/IEC 60947-2, with an Icn of 10 kA at 230 V AC per EN/IEC 60898-1 — sufficient for most commercial and light industrial panelboards where fault levels stay under 10 kA at the service entrance.
D-curve selectivity and coordination
The D-curve characteristic (12 x In magnetic trip) is the key differentiator from the more common C-curve (5–10 x In). For a 25 A circuit, the D-curve allows a short-duration inrush up to roughly 300 A before the magnetic trip operates, which is essential for motor starters, small transformers, or banks of LED drivers that draw a high starting surge. The trade-off is reduced sensitivity to lower-level short circuits, so coordination with upstream devices should be verified during panel design.
Mounts on a 35 mm DIN rail with a 2-module width (18 mm per pitch, 9 mm pitch count of 2). Terminals accept 1–25 mm² rigid or 1–16 mm² flexible conductors; strip length is 14 mm and tightening torque is 2 N·m. The IP20 finger-safe enclosure suits clean indoor panels only — not washdown or outdoor environments. A toggle control with a trip-indicator flag provides local visual status.