The Schneider Electric A9R14263 is a 2-pole residual current circuit breaker (RCCB) from the Acti9 iID family, rated 63 A continuous current with 300 mA earth-leakage sensitivity. The tripping is voltage independent, so it clears a ground fault even if the line voltage collapses.
The breaking capacity is 1500 A (Idm and Im both 1500 A), which covers most sub-distribution fault levels; if your upstream breaker can deliver more, you'll need to check coordination. The insulation voltage is rated 500 V AC, so the internal clearances are good for a 277/480 V system if you're using it in a delta or corner-grounded configuration (but the coil is still 240 V). Earth-leakage protection is instantaneous — no intentional time delay. That means it trips as soon as the residual current exceeds 300 mA, which is fine for general shock protection (the 300 mA threshold is typical for fire protection or equipment ground-fault, not personnel shock — personnel protection usually calls for 30 mA). The 8/20 µs impulse withstand of 250 A means it won't nuisance-trip on lightning surges or switching transients up to that energy level.
Durability and environmental fit
Mechanical durability is 20,000 cycles; electrical durability under AC-1 (resistive load) is 15,000 cycles — that's a solid service life for a distribution board that doesn't see daily switching. The operating temperature range is -5 to 60 °C, and storage from -40 to 85 °C, so it's fine in an unheated enclosure as long as the ambient stays above -5. IP20 on the terminals, IP40 inside a modular enclosure — keep it behind a panel door or in a cabinet; it's not rated for washdown.