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The primary electrical supply must be reliable and dependableThese two terms are not defined in NFPA 72. It is very difficult to put into words a requirement that is likely to vary based on geographic location. For example, even though there is normal utility power very available in California, if the site is on an active earthquake fault, is it dependable? The authority having jurisdiction has great latitude in determining reliability and dependability. and not subject to long, continuous outages.
In remote locations you may need to take extra precautions. For example, an American school located in an underdeveloped country where "normal" power doesn't exist will need a generator for the primary power. Trained operators will also need to be onsite at all times.
Today, there is no allowance for the elimination of batteries as a secondary power supply to fire alarm systems. If a generator is connected to a dedicated circuit serving only the fire alarm system directly, or if there is a pair of generators at a remote site as the primary power supply, the fire alarm system is still required to have batteriesSecondary power requirements were allowed to be eliminated until the 2002 edition of NFPA 72, but with specific requirements. However, this requires an extremely reliable primary power supply and a generator. The generator, in this design, backs up the primary power supply and is not considered a secondary unit. This arrangement is outlined in NFPA 72-1999, National Fire Alarm Code, Section 1-5.2.3, and in NFPA 70-2002, the National Electrical Code©, Articles 700, 701 and 702. However, this allowance was removed from NFPA 72 entirely when the 2007 edition was published. that can carry the fire alarm system for a period of at least four hours.
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