When heat detectors are installed on peaked ceilings, a row of detectors must be spaced and located at or within ___ of the peak, measured horizontally.

• A. 2 ft
• B. 4 ft
• C. 6 ft
• D. 3 ft

Answer: (D)

Heat rises and collects along the ceiling, with the apex of a peaked ceiling being the first place where heat concentrates. To ensure a heat detector responds quickly in that high-heat region, detectors on a peaked ceiling are placed within a short horizontal distance from the peak. The standard guideline is within three feet of the peak, measured horizontally along the ceiling.

So, the best answer is three feet because it places the detectors close enough to the apex to sense a rapid temperature rise, while still allowing proper spacing along the row. Placing detectors farther away (four or six feet) could delay detection in the apex area, and placing them much closer (two feet) isn’t necessary given the established spacing rule.