Nevada Fire Alarm Technician (F-Card) Practice Exam

Heat detectors require a conservative spacing plan to ensure timely detection under real-world conditions. The listed spacing from the detector’s listing is based on ideal test conditions, so you apply a derating factor to account for things like ceiling height, air movement, and temperature variations that can slow response.

Multiply the manufacturer’s listed spacing by 0.64 to obtain the maximum allowable spacing in the field. For example, if the listed spacing is 10 feet, the practical maximum spacing becomes 6.4 feet. This 0.64 factor keeps coverage conservative and aligned with how heat detectors perform in actual installations, rather than relying on the idealized listing.