Which signal is not required to be transmitted from an interconnected suppression system control unit to the main fire alarm control unit?

• A. Alarm signal
• B. Supervisory signal
• C. Trouble signal
• D. Guard's tour

Answer: (D)

In an interconnected suppression system, the signals that flow from the suppression control unit to the main fire alarm control unit are three standard types: alarm, supervisory, and trouble. The alarm signal is sent when the suppression system is activated or a fire condition is detected, triggering building alarms and notifications. The supervisory signal confirms that critical components (like control valves or release mechanisms) are in the correct state, so the main panel can monitor system readiness. The trouble signal alerts to faults in the system or its wiring, prompting maintenance action.

The guard’s tour, on the other hand, is not part of this automatic signaling path. A guard’s tour is a manual activity used for fire watch or security procedures and isn’t a required transmission from the suppression control unit to the main fire alarm control unit. So it’s the signal not required to be transmitted.