Warning lights provide a visual indication of a hazardous situation. Some warning lights may be available as audio/visual alarm combinations.

Applications

Applications for warning lights may include:

• security
• burglary or theft
• fire
• machine failure or malfunction
• process monitoring
• power distribution
• confined space or personal safety
• smoke
• structural failure
• vehicle safety

Types

Warning lights are available in many types. Safety strobe lights are flash lamps that produce high-intensity, short-duration light pulses by electric discharge in a gas. Revolving emergency lights are often available in colors and for mounting on vehicles. Flashing lights alternate between on and off when in the powered position. Light bars are warning packages often containing one or more strobe light bars or revolving or flashing lights. Light panels are alarm systems where the visual indication is provided by a panel display lit with lamps or bulbs. Special types of warning lights may be (or may contain) a digital display (like that of an LED warning light or LCD) or a computer or video monitor.

Features

The flash rate represents the number of times the strobe or flashing light flashes in one minute. Flashing alarms may consist of a single flash of the lamp, double flash, triple flash, quad flash, or more. Visual alarms that do not flash provide a continuous visual output. The alarm may provide built-in synchronization. NFPA 72 requires visual appliances to flash in synchronization in rooms or areas where there are two or more visual devices that are not a minimum of 55 feet apart. NFPA 72 requires that fire alarm signals be distinctive in sound from other signals and used for that purpose only. This is known as the three-pulse temporal pattern. The power of the lamp/bulb is measured in watts (W). Warning lights may be available in a number of colors to represent different alarm levels. The lens color may be clear, red, amber, yellow, green, blue, purple, or another special or proprietary color. AC or DC voltage supplies the visual alarm. A feature of some warning lights is battery backup.

Warning lights are often equipped with a number of other features, which may include:

• acknowledge or silence
• explosion-proof housings
• intrinsically safe operation warning lights
• outdoor ratings
• selectable candela
• submersible housings

Related Information

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