This Miniature Circuit Breaker is a thermal-magnetic current limiting type, having a compact construction which has been achieved by not only minimising the number of parts but also the number of welded joints and connections. The MCB has an easy to operate handle with a trip-free toggle mechanism – so even when the handle is held in the ‘on’ position the MCB is free to trip. Single pole MCBs with Type B characteristics (3-5In) are suited for use on loads with little or no switching surges, such as occur on domestic applications. Back-up protection is required only if the prospective short circuit current at the point of installation exceeds the breaking capacity of the MCB. When providing back-up protection consideration must be given to discrimination between the MCB and fuse.