Which of the following is not an initiating device?

• A. A duct smoke detector
• B. A water flow switch
• C. A tamper switch
• D. A strobe

Answer: (D)

In a fire alarm system, initiating devices are what start the alarm signal. Duct smoke detectors and water flow switches actively sense a hazard and trigger the control panel to initiate the alarm. A tamper switch is typically a supervisory device that monitors for tampering or faults rather than starting the alarm. A strobe is a signaling/notification device; it alerts occupants once the alarm is already active but does not initiate the alarm itself. Therefore, the one that is not an initiating device is the strobe.