The Schneider Electric A9R84240 is an Acti9 iID residual current circuit breaker (RCCB) — a 2-pole, 40 A, 300 mA sensitivity device for AC networks at 220…240 V, 50/60 Hz. The 300 mA trip threshold makes it a common choice for general-purpose protection where a higher leakage tolerance is acceptable, like submain or feeder circuits rather than individual socket-outlet protection.
That matters: if the downstream load includes VFDs, UPS systems, or LED drivers that can generate pulsed or DC leakage, a Type A or Type B RCCB would be needed instead. The instantaneous trip (no intentional time delay) means it clears a ground fault within a few cycles — fine for most general circuits, but not for selectivity with downstream RCDs unless you coordinate via a separate time-delay device. The breaking and making capacity is rated at 1500 A (Idm and Im) per EN/IEC 61008-1. The surge current withstand is 250 A (8/20 µs impulse), which covers typical lightning-induced transients on the AC mains. IP20 on the body (finger-safe), IP40 inside a modular enclosure — standard for indoor panel mounting. The terminal range accepts up to 35 mm² rigid or 25 mm² flexible, with a stripping length of 14 mm and a tightening torque of 3.5 N.m. Wire it with the neutral on the left side (fixed position).