Which device is used to isolate a section for maintenance or testing and is not typically used to interrupt fault currents?

• A. Circuit breakers
• B. Fuses
• C. Reclosers
• D. Disconnect switches

Answer: (D)

The device used to isolate a section for maintenance or testing is the disconnect switch. Its purpose is to create a clear, visible break in the circuit so personnel know that the section is deenergized and safe to work on. Because its primary role is to provide isolation, it’s not typically relied on to interrupt fault currents—those duties belong to protective devices with higher interrupting ratings, such as circuit breakers or fuses, which are designed to detect faults and stop current flow. Reclosers also interrupt currents as part of automatic restoration cycles, but their job isn’t isolation for maintenance. So a disconnect switch is the best choice for safe, visible isolation without handling fault-current interruptions.