A9F54440 MCB Mini Circuit Breaker 4P, 40 A. The Acti9 Disbo series of MCBs by Schneider Electric provides excellent circuit protection particularly in combating short circuits and overload currents. These MCBs are rigorously tested by Schneider and are compliant with standards such as IEC/EN 60898 & 60947-2. These types of MCBs are typically used in industrial or commercial buildings and can work extremely well in polluted environments.