A wall-mounted spot-type heat detector shall be within 12 inches of the ceiling.

A wall-mounted spot-type heat detector shall be within 12 inches of the ceiling.

• A. 6 Inches
• B. 9 Inches
• C. 12 Inches
• D. 18 Inches

Answer: (C)

Heat detectors respond to a rise in temperature, so they are placed high enough to be in the warm air that rises toward the ceiling. When a wall-mounted unit is used, it should be located no more than 12 inches below the ceiling to ensure it sits in that heat layer and can detect a fire quickly. This distance provides the quickest response while still being practical for wall mounting. Distances shorter than that meet the rule, but placing it farther than 12 inches—like 18 inches—would exceed the allowed placement proximity to the ceiling and could delay detection.

Heat detectors respond to a rise in temperature, so they are placed high enough to be in the warm air that rises toward the ceiling. When a wall-mounted unit is used, it should be located no more than 12 inches below the ceiling to ensure it sits in that heat layer and can detect a fire quickly. This distance provides the quickest response while still being practical for wall mounting. Distances shorter than that meet the rule, but placing it farther than 12 inches—like 18 inches—would exceed the allowed placement proximity to the ceiling and could delay detection.