What must be true of the test smoke used to test detectors?

• A. Shall be listed for use and shall be approved by the detector's manufacturer
• B. Must be approved by the AHJ
• C. Need not be listed for use
• D. Should be used only during normal operations

Answer: (D)

Testing detectors with smoke is about how the test is conducted safely and reliably. The statement that must be true is that test smoke should be used only during normal operations. Keeping testing within normal operating conditions ensures a controlled, predictable environment so you can verify the detector’s response without the complications of an active incident. If testing were done during abnormal conditions or ongoing emergencies, the test could be mistaken for a real fire, cause unnecessary evacuations, or cloud the assessment of the detector’s true performance. In practice, follow the manufacturer’s guidance for the test smoke itself, but the key point emphasized here is scheduling and performing tests only when the system is in its normal operating state.