Power Design Inc

2010 NFPA 72 CODE REFERENCE
CHAPTER: 17 Initiating Devices
ARTICLE: 7 Smoke-Sensing Fire Detectors
17.7.1.11 Protection During Construction
Many needless alarms are caused by smoke detectors installed too early in the construction process. Construction activities produce airborne dust that inevitably finds its way into detectors, contaminating them and making them prone to false alarms. History, however, shows that fires often occur during renovation and construction because these activities include numerous fire ignition sources. Often smoke detection is required in areas under construction for that very reason. If smoke detection is required in the area under construction or renovation, 17.7.1.1 1 establishes the requirements for cleaning and sensitivity measurement or replacement. Where the authority having jurisdiction requires early installation, detectors installed prior to the completion of final finish work must be cleaned and measured for their normal operating sensitivity. Those detectors found outside their design sensitivity range must be replaced.
17.7.1.11 Construction debris, dust (especially gypsum dust and the fines resulting from the sanding of dry wall joint compounds), and aerosols can affect the sensitivity of smoke detectors and, in some instances, cause deleterious effects to the detector, thereby significantly reducing the expected life of the detector.
17.7.1.11.1 Where detectors are installed for signal initiation during construction they shall be cleaned and verified to be operating in accordance with the listed sensitivity, or they shall be replaced prior to the final commissioning of the system.
17.7.1.11.2 Where detectors are installed but not operational during construction, they shall be protected from construction debris, dust, dirt, and damage in accordance with the manufacturer’s recommendations and verified to be operating in accordance with the listed sensitivity, or they shall be replaced prior to the final commissioning of the system.
The requirement in 17.7.1.11.2 is new in the 2010 edition. If detectors are installed before completion of construction cleanup, they must be protected in accordance with the manufacturer's instructions.
Many smoke detectors are shipped with a thin plastic cover over the sensing portion of the detector. It is widely assumed that these covers are suitable for protecting the detector from construction dust, dirt, and debris. In actuality, most of the "covers" supplied are merely for shipping and are not intended to be used in lieu of proper protection from construction debris. In some cases, the authority having jurisdiction may allow the installation of protective covers. However, these covers cannot be relied on to keep the detector entirely free of contaminants. Therefore, sensitivity measurement and cleaning of the detectors after all construction trades have finished their work will probably still be necessary. If covers are used, the contractor must also have a means of verifying that they all have been removed when the construction trades have completed their work. If the authority having jurisdiction requires the covers to be removed at the end of each day, a good practice is to number the covers to ensure that all have been removed and then to replace them the next morning. Again, if the covers are removed during the construction process, it will be necessary to inspect the detectors closely, cleaning them when necessary, and testing them to ensure that their sensitivity is within the listed and marked sensitivity range. See Exhibit 17.23 for an example of a smoke detector protective cover.
17.7.1.11.3 Where detection is not required during construction, detectors shall not be in- stalled until after all other construction trades have completed cleanup.
Many needless alarms are caused by smoke detectors installed too early in the construction process. Construction activities produce airborne dust that inevitably finds its way into detectors, contaminating them and making them prone to false alarms. Unless detection is required while the area is under construction, experience has shown that the best practice is to not install smoke detectors until all construction cleanup is completed.
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