scope:

The NEMA Signaling Protection and Communication Section developed this guide. It provides technical information on basic fire alarm systems with a focus on early-warning smoke detection devices installed in duct applications. Duct-mounted smoke detectors are designed to provide a specific type of protection that cannot be duplicated by any other type of system. However, there has been a tendency to misapply these devices attempting to use them as a substitute for an early warning smoke detection system. This fact, coupled with new methods of detecting smoke in ducts, has prompted the Section to write this industry guide. Aspirated smoke detectors may also be listed for use in detecting smoke in ducts but are not addressed in this guide due to their specialty nature. Similarly, duct-mounted carbon monoxide detectors are also out of scope since they are not used to detect smoke.