What this RCCB does on the line
The Schneider Electric A9Z11440 is an Acti9 iID residual current circuit breaker (RCCB) — a 4-pole, 40 A device with 30 mA earth-leakage sensitivity for AC networks. The 30 mA trip threshold catches leakage currents that would be imperceptible but dangerous through a human body; the instantaneous response means it clears without intentional delay, so it's the primary protection device on the branch circuit, not a time-delayed unit for selectivity coordination.
Rated at 40 A (In) and 380-415 V AC, 50/60 Hz, this RCCB handles the full load current of a typical three-phase sub-distribution or a large single-phase final circuit. The 30 mA sensitivity is the standard for personal protection in most residential, commercial, and light industrial installations per IEC 60364. Type AC detection means it trips on sinusoidal AC residual currents only — suitable for circuits without electronic loads that generate pulsed or DC fault currents. The voltage-independent residual current tripping technology means the RCCB operates even if the supply voltage collapses during a fault — the trip mechanism derives its energy from the leakage current itself, not from the line voltage. This is a reliability advantage over electronically tripped RCCBs in installations where a neutral loss could otherwise disable protection.
Clip-on mounting to a standard DIN rail, 8 module pitches wide (72 mm per pitch, 8 pitches = 72 mm width). Tightening torque 3.5 N.m. IP20 finger-safe with the modular enclosure providing IP40 in the panel.