The ceiling height is 15. The heat sensor spacing should be ___% of its listed requirement.

In fire alarm systems, the spacing of heat detectors is typically determined by the ceiling height, as the height can affect the performance and reliability of the detectors. For ceilings that exceed a standard height, adjustments to the spacing requirements are necessary to ensure that the detectors can effectively sense changes in temperature.

When the ceiling height is greater than 10 feet, the National Fire Protection Association (NFPA) guidelines recommend that heat detectors be spaced closer together than they would be under standard conditions. Specifically, for a 15-foot ceiling, the heat sensor spacing should indeed be reduced to 77% of its listed requirements.

This percentage adjustment accounts for the increased distance that the heat from a fire has to travel before being detected by the sensor, ensuring that the system remains effective in a taller space. Using 77% of the listed spacing allows for adequate coverage while taking into consideration the properties of heat dissipation in a room with higher ceilings.