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 188.8.131.52 (rooms), 184.108.40.206
(corridors), and 220.127.116.11/18.104.22.168 (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.
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).