MCCB Mould Case Circuit Breakers can automatically cut off the current when the current exceeds the trip setting. Molded plastic insulator refers to a housing unit for isolation between the conductor and the grounded metal parts. Molded case circuit breakers usually contain thermal magnetic trip units, although larger sizes MCCB equipped with solid state trip sensors. Its trip unit is divided into: thermal magnetic and electronic trip unit trip. Common rated current total of the following 15 25 30 40 50 60 75 80 100 125 160 200 225 250 315 350 400 500 630 A.