The BR and SU series DIN rail-mounted, thermal magnetic miniature circuit breakers (MCB) are UL 489-listed branch circuit breakers and UL 1077-listed supplementary circuit breakers. They are rated for both ac and dc circuits. Suitable for use in environments in which the control equipment may be subjected to vibration and mechanical shock, the circuit breakers provide downstream protection for circuit cables, motors, generators, transformers, computer systems, power supplies and telecommunications equipment. They are equipped with a trip-free, snap-action toggle and visual status indication. At 17.6 mm wide (one pole), they are available in one-, two- and three-pole versions with an amperage range up to 63 A.