What this RCCB does and where it fits
The Schneider Electric A9R81225 is a 2-pole residual current circuit breaker (RCCB) from the Acti9 iID family, rated 25 A with 30 mA earth-leakage sensitivity. It's a Type AC device — meaning it detects sinusoidal AC residual currents only, not pulsed DC or high-frequency waveforms. That makes it a straightforward choice for general-purpose circuits feeding resistive or lightly inductive loads where the fault current is expected to be plain AC. The 30 mA threshold is the standard for personal protection against indirect contact in residential and commercial final circuits. It clips onto a DIN rail (35 mm symmetrical rail per EN 60715) and occupies 4 modular pitches of 9 mm each — 36 mm wide total. The neutral is on the left, which matters when laying out a row of devices in a panel so the busbar alignment stays consistent. Breaking capacity is 1500 A (Idm and Im both), which is typical for an RCCB in a domestic or light commercial distribution board — enough to handle the prospective fault current downstream of a 63 A main switch.
Installation and wiring notes
Terminals accept 1 to 35 mm² rigid cable, or 1 to 25 mm² flexible (with or without ferrule). Strip length is 14 mm for both top and bottom connections. The toggle control is manual, with a contact position indicator that shows green/red status on the face. There's also a padlocking option to lock the device in the OFF position for lockout/tagout during maintenance.