A Molded Case Circuit Breaker (MCCB) is a required component of electrical systems, providing overload protection and short-circuit protection. In most cases, MCCBs are installed in the main power distribution board of a facility, allowing the system to be easily shut down when. A single phase distribution box is where you control electricity at home or work. You can trust a single phase distribution box to help your circuits work well and stay. Circuit breakers are classified by voltage level (low, medium, high), arc-quenching medium (air, vacuum, SF6, oil), application (residential, commercial, industrial), and trip characteristics (Type A, B, C, D). But installing them correctly is non-negotiable.