Which safety device is applied when de-energizing the Third Rail to indicate a hazardous condition?

• A. Third Rail warning device
• B. Ground fault monitor
• C. Visual flag
• D. High visibility vest

Answer: (A)

When you de-energize the Third Rail, you must clearly communicate the hazardous condition so others recognize the danger. The Third Rail warning device is the specific signaling tool designed to indicate that the third rail is de-energized. It provides a clear, standardized indication that power is cut off and the area is hazardous, helping prevent accidental contact. Ground fault monitors are for detecting electrical faults, not signaling a de-energized condition. A visual flag is a general warning method, but the device used for this purpose in third-rail work is the Third Rail warning device. Wearing a high-visibility vest is PPE and does not indicate the de-energized state.