The Schneider Electric A9R40440 is a 4-pole residual current circuit breaker (RCCB) from the Acti9 iID K series, rated 40 A with 30 mA earth-leakage sensitivity. It is a Type AC device, meaning it detects sinusoidal alternating residual currents — the standard choice for general-purpose circuits where no pulsed or DC fault currents are expected. The 30 mA threshold is the common protection level for personal shock hazard in residential and commercial final circuits. The RCCB is voltage-independent in its tripping technology — it does not require an external power supply to detect a leakage fault and open the circuit. This is a reliability advantage: even if the neutral is lost upstream, the device still provides earth-leakage protection.
The 40 A rated current (In) sets the continuous load capacity. Breaking and making capacity is rated Idm 500 A / Im 500 A. This is the fault-current rating under residual-current conditions; for prospective short-circuit currents above 500 A, an upstream overcurrent protective device (MCB or fuse) must provide backup protection. The RCCB itself has no overcurrent protection — it is a pure earth-leakage device. The device carries an 8/20 µs impulse withstand of 200 A per EN/IEC 61008-1, meaning it can survive typical surge currents from lightning or switching without nuisance tripping or damage. Pollution degree 2 (non-conductive pollution only, occasional condensation) covers most indoor panel environments. IP20 protection on the body (finger-safe) and IP40 within a modular enclosure (tool-safe) — standard for distribution boards.
Neutral is on the left (neutral position: left). Depth is 69 mm, height 85 mm, width 72 mm (8 x 9 mm pitches). A padlocking device is available for lockout/tagout. The toggle control is manual; there is no contact-position indicator. Mechanical durability is rated at 5000 cycles, electrical durability (AC-1 resistive load) at 2000 cycles — sufficient for normal switching duty in a distribution board where the RCCB is operated infrequently (typically only for testing or isolation).