Which statement best describes a supervisory signal?

• A. Activates notification appliances when fire detected
• B. Indicates a true fire condition
• C. Initiates a manual alarm
• D. Indicates a monitored condition such as release devices, valves, or power loss

Answer: (D)

Supervisory signals alert when a monitored device that must stay in a specific state is not in that state (or when its power supply changes). They don’t indicate a fire themselves; they warn that critical components aren’t ready, so building staff can correct it before a fire occurs. Examples include release devices and valves in the fire protection system, and the power feeding those devices. If a releasing mechanism is actuated or a valve position changes, a supervisory signal is sent to the fire alarm control panel. If the power to those components is lost or interrupted, a supervisory condition is also indicated. This allows maintenance to restore the intended state, ensuring the system will perform properly in an emergency. In contrast, an alarm signal comes from actual fire conditions, a manual alarm is started by someone activating a manual station, and a trouble signal points to faults or malfunctions in the system.