A thermal-magnetic trip unit is provided for a circuit breaker. The thermal-magnetic trip unit includes a heater and a translational magnetic system coupled to the heater. The heater includes a first portion, a second portion, and a third disposed between the first portion and the second portion. The first portion has a first surface disposed in a first plane, and the second portion has a second surface disposed in a second plane that is substantially parallel to the first plane. The first surface is separated by a first predetermined distance from the second surface. The third portion has a third surface disposed in a third plane that is substantially perpendicular to the first plane. The third surface has a first predetermined length and is separated by a second predetermined distance from the second surface. Numerous other aspects are provided.