The Schneider Electric A9R34492 is a 4-pole Acti9 RCCB-ID residual current circuit breaker rated at 125 A and 300 mA earth-leakage sensitivity, with a Type A-SI (Super Immunised) characteristic. The 125 A continuous rating handles the full load of a sub-distribution board or a large single load on a 400 V AC three-phase network. The 300 mA sensitivity is a standard for protection against fire risk from earth faults in industrial or commercial final circuits — it's less sensitive than the 30 mA needed for personal shock protection, so it's typically used as a main incomer or for feeders where nuisance tripping from equipment leakage would be unacceptable. This makes it a practical choice on mixed-load outgoing circuits where drives or electronics are present. Breaking capacity is rated at 1250 A at both 400 V and 230 V per IEC/EN 61008-1 and IEC/EN 61008-2-1. In practice, this means the A9R34492 is sized for distribution boards where the upstream breaker or fuse limits let-through energy to within its 1250 A making/breaking envelope.
The 72 mm width occupies 8 modules of 9 mm pitch, so it fills four standard 18 mm pole positions. Tunnel-type terminals accept 1.5 to 50 mm² rigid or 1.5 to 35 mm² flexible cable on the main circuit, with dual-terminal capability for daisy-chaining up to 16 mm². Stripping length is 11 mm; tightening torque is 3 N·m. IP20 rated per IEC/EN 60529 for the body; IP40 in a modular enclosure. The red/green trip indicator and padlockable toggle give clear local status and allow lockout/tagout during maintenance.
Compliance documentation is defined by the cited standards: IEC/EN 61008-1 and IEC/EN 61008-2-1 for residual current device performance, plus VDE quality label. The part carries CE marking as a Schneider product sold into the European market. RoHS and REACH declarations are standard for Schneider's Acti9 range; specific certificates are available from the manufacturer upon request.