The Schneider Electric A9N21370 is a Prodis DT40N miniature circuit breaker rated 40 A with a C-curve trip characteristic (magnetic tripping at 5 to 10 times In). The 1P+N pole configuration protects one live conductor and switches the neutral, common in single-phase distribution boards where neutral switching is required. Breaking capacity is 6 kA Icn per EN/IEC 60898-1 at 230 V AC, and 10 kA Icu per IEC 60947-2 at 230–240 V AC — the higher Icu figure matters when the breaker is applied in an industrial panel under the 60947-2 standard, where fault currents may exceed the domestic 6 kA limit.
Depth 78 mm, height 81 mm — fits standard 80 mm deep enclosures with a few mm to spare. IP20 finger-safe terminals are fine for enclosed panels but not for washdown areas.
Dual-certified to EN/IEC 60898-1 (domestic MCB standard) and EN/IEC 60947-2 (industrial circuit-breaker standard), so it qualifies for both residential and light-industrial panels. NF quality label.