Fire Alarm Strobe candela requirement

Questions about Georgia Codes and Standards

Fire Alarm Strobe candela requirement

Postby Blackstone on Thu Nov 20, 2008 10:55 pm

Accessible Visual Alarm

120-3-20-.39(3)(d) indicates a minimum intensity of 75cd (candela) is required for visual alarms. This intensity is a minimum performance criterion – not a lamp sizing or specifying standard – and is required within a 50-ft radius. The performance criterion of a 75cd visual alarm at 50-ft raises the ambient light level by 0.03 lumens/ft2 (inverse square law), and is thus the scoping provision for accessible visual notification appliances. Visual alarm devices installed in accordance with the spacing requirements of NFPA 72 (2002), Sections (rooms), (corridors), and (sleeping areas) using the UL 1971 candela listing for the device, comply with the this scoping requirement. A minimum 75cd device is not required by accessibility standards, but rather a UL 1971 listed device providing the minimum 0.03 lumens/ft2 illumination throughout the device’s area of coverage per NFPA 72 (2002), Section 7.5.

Visual devices indicated to be 15/75cd (15cd per UL 1971 for indirect viewing ~ 75cd per UL1638 for direct viewing) are an example of devices complying with this 75cd requirement, yet also complying with the requirement that all notification appliances be listed for UL 1971 “Standard for Safety Signaling Devices for the Hearing Impaired”. These 15/75cd visual appliances are designed for corridor use in that the standards recognizes a person in a corridor typically travels facing along the corridor and can either view the appliance indirectly or directly. Visual appliances in rooms must comply with the UL 1971 rating only as a person may be facing in any direction (i.e. the UL 1638 direct viewing rating would not be applicable as they could be facing away from the device).
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