III. UNDERWRITERS LABORATORIES WARNING EXPLANATION.
“Warning‑Not to be used as a visual public mode alarm notification appliance”
WHAT DOES THIS MEAN?
Underwriters Laboratories uses two different standards to investigate and List visual signal applianc-
es. The first UL Standard for Safety is UL1971 - Signaling Devices for the Hearing Impaired. This
standard covers visual signaling devices intended for fire alarm systems to alert the hearing impaired.
The second UL Standard for Safety is UL1638 - Visual Signaling Appliances-Private Mode Emer-
gency and General Utility Signaling. While this standard may also cover visual signal appliances, it
does not include the determination of adequacy relative to alerting hearing-impaired individuals in a
fire alarm system.
To prevent misapplication of a visual signal appliance Listed to UL1638, UL determined it is the
manufacturer’s responsibility to warn the installer in the field and Authority Having Jurisdiction
(AHJ) of what would be an inappropriate use of the product. Therefore, manufactures whose prod-
ucts Listed to UL1638 are required by Underwriters Laboratories to bear the warning, “Warning ‑
Not to be used as a visual public mode alarm notification appliance”.
“Public Operating Mode” and “Notification Appliance” as defined in the National Fire Alarm Code,
NFPA 72 is as follows:
Public Operating Mode - Audible or visible signaling to occupants or inhabitants of the area pro-
tected by the fire alarm system.
Notification Appliance - A fire alarm system component such as a bell, horn, speaker, light, or text
display that provides audible, tactile, or visible outputs, or any combination thereof.
In other words, this device should not be used as a component of a commercial fire alarm system.
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