The 140U-J3D3-D12 Molded Case Circuit Breaker or MCCB is a high-performance compact circuit breaker from Allen-Bradley/Rockwell Automation. It has a size J frame, 3 poles, and 250 Amps of frame current. The rated operational voltage of the breaker is 400 to 480 Volts AC and the amperage rating is 125 Amps. The 140U-J3D3-D12 Molded Case Circuit Breaker comes with 35 Kiloamps of interrupting rating and it weighs approximately 11.4 pounds. It is a mechanical switching device that is capable of breaking an electrical circuit under a short circuit condition. In normal circuit conditions, the breaker can be used to carry and break the current. The arc chamber of the MCCB and its components provide the facilities to cool the contact after a short circuit.

The 140U-J3D3-D12 Molded Case Circuit Breaker shares the same accessories with the MCPs and other MCCBs from Allen-Bradley while maintaining the maximum level of flexibility and cost-saving. It has a reliable safe design that prevents access to live parts when the cover is removed. It can be used as a motor branch protective device that is capable of carrying the starting current of the motor. This breaker complies with the UL 489 current limiting guidance and performance levels. Mounting the 140U-J3D3-D12 MCCB in any position, up, down, horizontally, or vertically, does not affect the tripping of the breaker. This circuit breaker can be mounted individually in a separate enclosure. Applications with large electrical generators use this breaker to provide reliable protection for the applications. It can be used as a manual disconnection switch during maintenance or an emergency. This molded case circuit breaker is suitable for large commercial and industrial applications.