Which color indicates Out of Service?

• A. Green
• B. Gray
• C. Yellow
• D. Orange

Answer: (D)

Color cues are used for quick, at-a-glance status. Orange is used to indicate Out of Service because it stands out and signals a temporary condition that the equipment or service should not be used. It’s distinct from green, which generally means everything is in operation, and from yellow, which often means caution or limited service, and from gray, which commonly denotes not in service or unavailable. Seeing orange tells you to expect a stop or a maintenance window and to avoid using that component until it’s back in service.