To ensure they are working properly, security lights should be checked what prescribed period of time before sunset?

The correct answer is 30 minutes because security lights are designed to illuminate an area and enhance safety during nighttime operations. By checking the lights 30 minutes before sunset, personnel can ensure that the lights have sufficient time to be tested under conditions similar to those they will experience after dark. This timeframe allows users to confirm that the fixtures are operational, adjust settings if necessary, and address any maintenance issues before the lights are needed for actual security purposes at dusk. This proactive approach is essential for maintaining effective security protocols and ensuring that illumination is available as soon as natural light diminishes.