What the 25 kA interrupting rating means for your panel
The ABB XT1NU3110AFF000XXX is a 3-pole molded case circuit breaker from the XT1N family, rated for 25 kA interrupting capacity at 400 VAC. In a 400 V distribution board, 25 kA covers most commercial and light industrial service-entrance conditions; if your available fault current runs higher, you would step up to the XT1H or XT1L series with 36 kA or 50 kA ratings.
Its compact 3-pole footprint (45 mm per pole) fits standard distribution boards and motor control centers. The line and load terminals accept copper or aluminum conductors up to 50 mm², with a torque rating of 3.5 Nm for the main connections. For field-service swaps, the breaker's plug-in base option allows replacement without disturbing the busbar connections — a time-saver on a live panel during a line-down event.