What the 225 TMF frame means
The 225 TMF designation refers to the thermal-magnetic trip unit and the frame size — the XT3N 225 frame is rated for continuous currents up to 225 A. This is the frame that determines the physical footprint, bus-bar spacing, and mounting pattern in the panel. The TMF trip provides standard overload (thermal) and short-circuit (magnetic) protection, suitable for general distribution and motor branch circuits.
Panel integration
Fixed thermal-magnetic trip means no interchangeable trip units — the protection curve is set at the factory. Verify the lug kit matches your cable size before terminating.