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NOTE: This is an unformatted excerpt from our online fire protection training library.

Power Supplies


Primary Power Supplies

Each fire alarm system has a specific design that is never 100% generic. The goals of the system - Life Safety, Property Protection, Mission Continuity, Heritage Preservation, or Environmental Protection - directly impact the design.

The power supply is the first component of the fire alarm system. Like other electrical installations, the power supply must conform to the National Electrical Code (NFPA 70). A fire alarm system needs two independent power supplies, a primary and a secondary. Primary power normally connects to the building's light and power service. The secondary (or backup) power supply may be as simple as control-unit battery power or as complex as a combination of batteries and an engine driven generator. In the past, secondary power requirements could sometimes be eliminated. However, this required an extremely reliable primary power supply and a generator. Secondary power elimination is no longer allowed, as of the publication of NFPA 72-2007.  It was allowed in systems installed prior to the adoption of NFPA 72-2007, but only when the power supply conformed to the National Electrical Code, Articles 700, 701 or 702.

The fire alarm control unit requires a dedicated primary power circuit. This means that the fire alarm system's connection to the light and power service cannot be shared; the control unit must be the only connection on this circuit. The circuit breaker (or other circuit-disconnecting device) must have controlled access so that only authorized people can operate it. Circuit-disconnecting devices must be clearly marked in red at the circuit control, and the location of the circuit breaker must be identified at the fire alarm control panel.
NOTE: This is an unformatted excerpt from our online fire protection training library.

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