The Schneider Electric A9Z14440 is a 4-pole residual current circuit breaker (RCCB) from the Acti9 iID series, rated at 40 A with a 300 mA earth-leakage sensitivity. The 40 A rating and 300 mA threshold suit it for general-purpose protection on 380–415 V AC 50/60 Hz networks where nuisance tripping from transient leakage is a concern, such as distribution sub-mains or feeder circuits supplying multiple loads.
The 40 A rated current (In) governs the continuous load the RCCB can carry — sized for a 40 A feeder, not for individual branch circuits. The 300 mA sensitivity is higher than the typical 30 mA for personal shock protection; here it is intended for fire prevention and equipment protection on circuits where some leakage is normal. The breaking capacity (Idm/Im) is 1500 A — the maximum fault current the RCCB can interrupt on its own. The 6 kV rated impulse withstand voltage (Uimp) confirms it handles surge transients common in industrial environments. Electrical durability is 15,000 cycles under AC-1 (resistive) load, with 20,000 mechanical cycles — adequate for distribution panels that see infrequent switching.
The A9Z14440 clips onto a DIN rail (35 mm) and occupies 8 modules of 9 mm pitch — 72 mm total width. Neutral is on the left, poles are 4P. Terminals accept up to 35 mm² rigid or 25 mm² flexible wire, with a stripping length of 14 mm and a tightening torque of 3.5 N·m. The toggle control and contact position indicator give a clear visual of the contact state. A padlocking provision allows lockout/tagout during maintenance.