Which of the following statements about recessed mounting of a smoke or heat detector is true?

• A. Must be UL listed for recessed use
• B. Requires a dedicated 120V supply
• C. Can only be recessed if tamper-protected
• D. Should be listed and tested for recessed use

Answer: (D)

The key idea is that detectors installed in a recessed manner must be certified for that mounting method. A smoke or heat detector used in a recessed installation should be listed and tested for recessed use. This means the device and its mounting accessories have been evaluated by a recognized testing lab for performance in a ceiling cavity, including how air flows to the sensing chamber, how heat and smoke are drawn into the unit, and how the unit interacts with the building’s ceiling or fire-rated assemblies. When a device is listed for recessed use, you can trust it will behave as designed in that specific installation, meet code requirements, and maintain the intended sensitivity and response characteristics. Without that specific listing and testing, performance can be unpredictable, and installation may not comply with standards or warranty terms.

A dedicated 120V supply or tamper protection are separate considerations and not universal requirements for recessed mounting itself; some devices may use different power sources, and tamper protection is an additional feature rather than the defining factor for recessed installation.