20 A, 3-pole MCCB with 22 kAIC — what it means on a line
The ABB XT1SU3020AFF000XXX is a 20 A, 3-pole molded case circuit breaker (MCCB) with a thermal-magnetic trip (TMF) and a 22 kA interrupting capacity at 480 VAC. Rated for 480 VAC line-to-line and 600Y/347 VAC wye configurations, it covers the common North American 480/277 V distribution panel as well as 600 V class wye systems. The 20 A continuous rating is the load it can carry indefinitely without tripping; the TMF trip curve handles motor inrush and short-circuit events.
Panel-mount integration
This MCCB is panel-mount only — no DIN-rail adapter, no snap-on. The mounting pattern and lug layout are standard for ABB's XT1 frame, so it swaps into existing ABB panel cutouts or a new backplate. For a retrofit, check the bus-bar spacing and lug type (line/load) against what's already in the enclosure.
What the 22 kAIC buys you
The 22 kAIC at 480 VAC is the headline number for a panel designer or MRO planner. In a 480 V panel fed from a 500 kVA transformer, available fault current can hit 20–25 kA. A 22 kAIC breaker gives you headroom there; a 14 kAIC unit would need a current-limiting fuse upstream or a series-rated combination. This one stands alone in that range.