For interconnected electric power production sources, when one or more phases of the primary source opens, the output of interactive electric power production equipment shall be automatically ___ all ungrounded conductors of the primary source.

For interconnected electric power production sources, when one or more phases of the primary source opens, the output of interactive electric power production equipment shall be automatically ___ all ungrounded conductors of the primary source.

• A. Connected to
• B. Disconnected from
• C. Integrated with
• D. Monitored with

Answer: (B)

When interconnected power sources lose one or more phases, safety and backfeed prevention require that interactive power production equipment automatically disconnects from all ungrounded conductors of the primary source. This creates an immediate isolation (anti-islanding) so the equipment cannot feed power back into a de-energized grid, protecting line workers and equipment and preventing unstable conditions on the system. The ungrounded conductors are the live hot lines, so disconnecting from all of them ensures there’s no live path for current even if only part of the source is lost. Options like staying connected, just integrated, or merely monitored would not guarantee that the system remains isolated, which is why “disconnected from” is the correct requirement.

When interconnected power sources lose one or more phases, safety and backfeed prevention require that interactive power production equipment automatically disconnects from all ungrounded conductors of the primary source. This creates an immediate isolation (anti-islanding) so the equipment cannot feed power back into a de-energized grid, protecting line workers and equipment and preventing unstable conditions on the system. The ungrounded conductors are the live hot lines, so disconnecting from all of them ensures there’s no live path for current even if only part of the source is lost. Options like staying connected, just integrated, or merely monitored would not guarantee that the system remains isolated, which is why “disconnected from” is the correct requirement.