The A9R81240 is a Schneider Electric Acti9 iID residual current circuit breaker (RCCB) — a 2-pole, Type AC device rated 40 A with 30 mA earth-leakage sensitivity, designed for 220-240 V AC 50/60 Hz networks.
The 30 mA sensitivity (Type AC) catches sinusoidal AC earth faults only — no pulsed DC or smooth DC components. For circuits with rectified loads (washing machines, LED drivers, VFDs), you would need Type A or Type F instead. The 250 A 8/20 µs impulse withstand means it holds against surge currents from nearby lightning or switching transients without nuisance tripping — a common pain point on older RCCB designs. Voltage-independent trip technology means the RCCB disconnects on earth fault even if the line voltage collapses — a safety advantage over electronic RCDs that need a control supply.
Neutral is on the left. Terminals accept 1-35 mm² rigid or 1-25 mm² flexible (with or without ferrule); strip length 14 mm, torque 3.5 N.m. Padlocking provision for lockout/tagout. IP20 finger-safe on the front face; IP40 inside a modular enclosure. Pollution degree 3 (conductive or dry non-conductive pollution).