The distance between spot-type heat detectors shall not exceed their listed spacing, and detectors shall be within what fraction of the listed spacing measured at right angles from all walls?

The distance between spot-type heat detectors shall not exceed their listed spacing, and detectors shall be within what fraction of the listed spacing measured at right angles from all walls?

• A. One half
• B. One third
• C. One quarter
• D. One fifth

Answer: (A)

Spot-type heat detectors are spaced so that no point in the protected area can be farther than the listed spacing from a detector, ensuring adequate coverage between units. In addition, to prevent detection gaps along walls, each detector must be located within half of that listed spacing from every wall, measured perpendicularly from the wall to the detector’s location. This combination keeps coverage continuous from ceiling to walls, so the maximum distance to a detector near a wall is S/2, where S is the detector’s listed spacing. Therefore, the required fraction is one half.

Spot-type heat detectors are spaced so that no point in the protected area can be farther than the listed spacing from a detector, ensuring adequate coverage between units. In addition, to prevent detection gaps along walls, each detector must be located within half of that listed spacing from every wall, measured perpendicularly from the wall to the detector’s location. This combination keeps coverage continuous from ceiling to walls, so the maximum distance to a detector near a wall is S/2, where S is the detector’s listed spacing. Therefore, the required fraction is one half.