MCCB for panel builders — XT1N 125 frame with TMF trip
The ABB XT1NU4125AFF000XXX is a 4-pole XT1N 125 molded case circuit breaker with a TMF 125-1250 thermal-magnetic trip unit, front-front terminals, and UL/CSA certification. The 125 A frame and TMF trip give you adjustable thermal pickup and fixed magnetic short-circuit protection — a standard choice for feeder and branch-circuit protection in 480 V distribution panels.
What the TMF trip means for your coordination study
The TMF 125-1250 trip unit gives you a thermal adjustment range from 125 A to 1250 A (the frame rating sets the upper bound at 125 A continuous) and a fixed magnetic pickup. That thermal adjustability lets you fine-tune the breaker to the actual load current without swapping trip units — useful when the connected load isn't exactly at the frame rating. The fixed magnetic short-circuit protection means the instantaneous trip point is set at the factory and cannot be changed in the field, which simplifies coordination with downstream devices.
Panel integration — 4-pole, front-front terminals
Four-pole configuration covers three-phase plus neutral switching, common in North American distribution panels where the neutral is switched for service disconnection. Front-front terminals mean line and load connections are both on the front face — this simplifies bus-bar routing and reduces the depth required inside the enclosure. The XT1N 125 frame size fits standard MCCB mounting footprints; no special adapters needed for most panelboards.