The Schneider Electric A9R01291 is an Acti9 iID residual current circuit breaker (RCCB), 2-pole, rated 100 A with 30 mA earth-leakage sensitivity. It's a Type A device, meaning it detects sinusoidal AC residual currents plus pulsating DC residual currents — the standard choice for general socket-outlet circuits and most commercial loads. The 100 A rating handles the full incoming supply for a typical residential or light commercial distribution board, so this is sized as a main switch or a high-current submain protector, not a final-circuit device.
The instantaneous trip (no intentional delay) means it clears a ground fault in under 40 ms, which is what you want for shock protection. The voltage-independent tripping mechanism is worth understanding: it stores energy from the fault itself to open the contacts, so the RCCB still protects even if the neutral is lost upstream. That's a reliability feature you don't get from electronic RCDs.
Where it goes in the panel
This clips onto a DIN rail — 4 modules wide (9 mm pitches = 4, so 36 mm width). It's an outgoer device, meaning it sits downstream of the main switch or breaker, feeding the distribution circuits. The neutral is on the left, which matters when you're laying out busbars or pre-wired distribution boards.
Built and tested to EN/IEC 61008-1, the harmonized standard for RCCBs. Impulse withstand voltage is 6 kV, and the device survives 8/20 µs surge currents up to 250 A without nuisance tripping — important for installations with nearby lightning exposure or switching transients.