If a heat detector with a listed spacing of 50 feet is mounted on an 18'1" ceiling, what is the maximum allowable spacing?

If a heat detector with a listed spacing of 50 feet is mounted on an 18'1" ceiling, what is the maximum allowable spacing?

• A. 32 ft
• B. 50 ft
• C. 20 ft
• D. 60 ft

Answer: (A)

High ceilings change how heat reaches detectors, so spacing is tied to mounting height. Detectors are listed with a maximum spacing for standard ceiling heights (typically around 8–10 feet). When the ceiling is much higher—like 18 feet—the spacing must be reduced to keep detection within a reasonable time. Many listings specify a maximum of 32 feet for ceilings taller than about 15 feet. So, a heat detector with a listed spacing of 50 feet used on an 18'1" ceiling would be limited to 32 feet apart to comply with the listing and ensure reliable coverage. The other options either ignore the height factor or fall outside the listed guidance.

High ceilings change how heat reaches detectors, so spacing is tied to mounting height. Detectors are listed with a maximum spacing for standard ceiling heights (typically around 8–10 feet). When the ceiling is much higher—like 18 feet—the spacing must be reduced to keep detection within a reasonable time. Many listings specify a maximum of 32 feet for ceilings taller than about 15 feet. So, a heat detector with a listed spacing of 50 feet used on an 18'1" ceiling would be limited to 32 feet apart to comply with the listing and ensure reliable coverage. The other options either ignore the height factor or fall outside the listed guidance.