Which device is used to indicate the status of a circuit in a control panel?

Which device is used to indicate the status of a circuit in a control panel?

• A. Red indicator lamp
• B. Green LED
• C. Blue indicator lamp
• D. Yellow indicator lamp

Answer: (D)

The idea is that indicator devices on a control panel use color-coded signals to quickly convey a circuit’s condition. A yellow indicator lamp is chosen to represent a status condition—something notable to the operator but not a fault. It signals that the circuit is in a particular mode or state (such as standby, in-process, or awaiting input) that should be watched, without implying an emergency. Green typically means normal or ready, red signals a fault or alarm, and blue is used for other specific signaling. Because yellow clearly denotes a non-critical status, it’s the best match for indicating the circuit’s current state.

The idea is that indicator devices on a control panel use color-coded signals to quickly convey a circuit’s condition. A yellow indicator lamp is chosen to represent a status condition—something notable to the operator but not a fault. It signals that the circuit is in a particular mode or state (such as standby, in-process, or awaiting input) that should be watched, without implying an emergency. Green typically means normal or ready, red signals a fault or alarm, and blue is used for other specific signaling. Because yellow clearly denotes a non-critical status, it’s the best match for indicating the circuit’s current state.