Energy » Circuit Breakers » Molded Case Circuit Breakers (MCCB) » USA

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Overview

Molded case circuit breakers (MCCBs) are low-voltage protection devices that interrupt overloads and short circuits. They combine a molded insulating case with adjustable thermal-magnetic or electronic trip units, offering broad ampere ranges and high interrupting capacity. MCCBs are used in industrial panels, motor control and building distribution where precise trip settings and fault tolerance are required. Selection depends on frame size, trip type, voltage rating and interrupting capacity (kA).

FAQ

What should I consider when buying a used MCCB?

Check ampere rating, interrupting capacity (kA), trip unit type (thermal‑magnetic or electronic), frame vs. trip rating, physical condition, signs of overheating or corrosion, service history, and compatibility with your panel bus and standards.

How do I ensure an MCCB is shipped safely?

De‑energize and tag the breaker, protect and cap terminals, pack in a sturdy crate or pallet with moisture protection, immobilize the unit, use a carrier experienced with electrical equipment and insure the shipment.

What is a practical maintenance schedule for an MCCB?

Perform visual inspections monthly/quarterly, clean dust, torque terminals after installation, exercise trip mechanism and perform trip tests annually or per manufacturer, and run insulation/thermal checks yearly.