The Schneider Electric A9D16840 is an Acti9 IKQE RCBO — a combined residual current device and miniature circuit breaker in one 18 mm wide module. It protects a single-phase final circuit against overload, short-circuit, and earth leakage, all in a single DIN-rail unit. Rated 40 A with a 10 mA earth-leakage sensitivity and a 10 kA breaking capacity at 230 V AC, it is suited for circuits where both overcurrent and high-sensitivity ground-fault protection are required, such as socket outlets in wet areas or medical locations.
The 10 mA earth-leakage sensitivity is the key differentiator here — most RCBOs in this class are 30 mA. A 10 mA device trips on leakage currents as low as 6–10 mA, which means it catches the kind of leakage a person might not feel but that can be dangerous in wet or medical environments. The Type C curve means the magnetic trip operates at 5–10× In (200–400 A), so it handles motor inrush and capacitive loads without nuisance tripping, but still clears fast on a hard fault.
The neutral is on the left, which matters when you're laying out a row of RCBOs — you need to maintain consistent busbar polarity.