Abstract: A flux shifting circuit breaker trip device includes a permanent magnet for developing a holding flux to create a magnetic force on a plunger sufficient to hold it in its retracted position in opposition to a spring. An electromagnet energized under the control of a static trip unit develops flux in opposition to this holding flux, whereupon the spring becomes overpowering and propels the plunger to its extended position effecting a circuit protective trip function. Temperature responsive means are also included to increase the reluctance in a region of the holding flux path in response to an excessive ambient temperature condition within the breaker enclosure, whereupon the spring becomes empowered to motivate a thermal override trip function.