You are paralleling two alternators. The synchronizing lamps grow dim and are totally darkened as the synchroscope pointer approaches the 0° position. What does this indicate?

Correct Answer: Option D — the circuit breaker can be closed

Dark synchronizing lamps combined with the synchroscope pointer at the 12 o'clock (0°) position confirm zero phase difference, equal voltages, and matched frequencies, signaling the exact moment the main circuit breaker may be safely closed.