Visual Signals
In 1971, Space Age Electronics introduced the first visual notification appliance, the AV32 light plate (which was installed over an existing horn) and V33 remote light. Meanwhile, in 1978, Wheelock introduced the first horn/strobe notification appliances with its 700 series. The majority of visual signals throughout the 1970s and 1980s were white or red incandescent lights. In the 1980s, most new installations began to include visual signals, and more strobes started to appear. In the United States, the 1990 Americans with Disabilities Act (ADA) triggered changes in evacuation signaling methods to include the hearing impaired. Audible notification appliances would now have to include strobe lights with higher brightness intensity to alert the hearing impaired. This made incandescent lights inadequate for the purposes of the ADA. Many existing installations that did not include visual signals were retrofitted with strobe plates. These retrofit plates would allow for the easy installation of a strobe without replacing the audible signal. Later ADA codes also required that strobes be at least 15 candelas and have a flash rate of at least 60 flashes per minute (one flash per second). Companies such as Wheelock and Simplex discontinued their translucent strobes, and replaced them with new, clear, high-intensity strobes. Today, strobe synchronization is often used to synchronize all strobes in a uniform flash pattern. This is to prevent individuals with photosensitive epilepsy from potentially experiencing seizures due to unsynchronized strobes.
Read more about this topic: Fire Alarm Notification Appliance
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