MCCB Mold Case circuit breakers can automatically turn off the power when the current exceeds the trip setting. A molded plastic insulator refers to a housing unit for insulation between the conductor and the grounded metal parts. Molded case circuit breakers typically include thermal magnetic trip units, although larger MCCBs are equipped with solid state trip sensors. Its trip unit is divided into: thermomagnetic and electronic trip unit. Common nominal current sum of the following 15 25 30 40 50 60 75 80 100 125 160 200 225 250 315 350 400 500 630 A.