Which category of protective devices includes insulated case circuit breakers, low voltage power circuit breakers, and molded case circuit breakers?

• A. Ground fault circuit interrupters
• B. Overcurrent protective devices
• C. Arc fault circuit interrupters
• D. Residual current devices

Answer: (B)

Overcurrent protective devices are designed to interrupt electricity when the current is too high, protecting conductors from overheating during overloads or short circuits. Insulated case circuit breakers, low voltage power circuit breakers, and molded case circuit breakers all fall into this category because they are built to trip when current exceeds their rating or when a fault occurs. They’re commonly used in low‑voltage distribution to provide the main line protection against excessive current. Other devices like ground fault circuit interrupters, arc fault circuit interrupters, and residual current devices protect against different fault conditions—ground leakage, arcing faults, or leakage currents—and are not the general overcurrent protection category described here.