Fluorescent lamps were introduced at the 1939 World's Fairs in both New York and San Francisco. The introduction heralded a new light source of high efficiency, low brightness, long life, and a new physical dimension.
Fluorescent tubular lighting systems were first made by André Claude, inventor of the neon sign, in France in 1932. Under the Mazda lamp agreement, Westinghouse and General Electric obtained Mr. Claude's patent rights and developed the fluorescent lamp we know today.
After incandescents, fluorescent lamps are the second most common light source. They are the most common source used in commercial buildings, producing about two-thirds of our nation's illumination.
Fluorescent lamps can be categorized in a number of ways. You will see broad categories of fluorescent lamps defined by their size, shape, and operating characteristics. Another approach to categorizing lamps is by their operating circuits. Keep in mind that identifying a lamp usually includes both of these approaches.
- 4 to 5 times more efficient than incandescent, and an exceptionally long life (10 to 20 times greater than incandescent).
- Easy to maintain.
- Lamp life is greatly affected by the average number of hours the lamp is cycled on and off.
- The lamps are also low cost and available in a wide range of sizes and colors.
- Relatively low surface brightness and heat generation, and are relatively insensitive to small changes in building voltage. This can be very important where brownouts are common.
- Most lamps are relatively large and require a relatively expensive fixture.
- The ballasts in fluorescent fixtures can have an objectionable hum (some louder than others).
- Ballasts are now given a noise rating. Quiet ballasts are recommended for office areas, louder and less expensive ballasts can be used in industrial facilities.
- Fluorescent lamps are temperature sensitive and may have difficulty starting at low temperatures. Also, lumen output drops at low and high temperatures. Special ballasts are available for low and high temperature applications.
- While dimming of fluorescents is possible, it requires special, relatively expensive ballasts.
Fluorescent lamps come in many varieties, not only wattage and size but also in color. They have different color temperatures, which determines what color they look when you look at them. And they have different color rendition capabilities that affect what color objects appear under them. True color rendition is especially important for merchandise displays, grocery stores, beauty salons, and in industrial applications where the work being performed requires color matching.
Fluorescents are a good retrofit for incandescent lamps that operate a significant number of hours. Circular fluorescent lamps can be used where exposed socket incandescent bulbs are currently used. Compact or PL fluorescent lamps (available in 5-40 watts) can be substituted for many incandescent bulbs and will fit in many types of fixtures.
Facilities already using fluorescent lamps should consider high efficiency fluorescent lamp designs. They produce about the same amount of light, while saving about 10 to 15% of the energy usage.
Major lighting manufacturers now offer more energy-efficient and lower wattage fluorescents. While some of the replacement lamps may yield slightly less light, this may be perfectly acceptable in areas that were previously over lit. When selecting new fluorescent lamps, make sure they are compatible with existing ballasts. However, it may be cost- effective to replace the ballast as well. Furthermore, when clean new lamps are installed, and the diffuser and reflecting surfaces of the fixture are cleaned, there may be an increase in light output even with lower wattage. However, it will be important to keep the fixtures clean to maintain acceptable light levels.
Lamp sizes range from four watts to 215 watts. The efficiency (lumens per watt) of a lamp increases with lamp length (from four feet to eight feet). The reduced-wattage fluorescent lamps introduced in the last few years use from 10percent to 20 percent less wattage than conventional fluorescent lamps, depending on size. For most applications, the cool white and warm white lamps provide very acceptable color and energy efficiency ratings.
It's hard to believe, but in many cases, it pays to replace your present lamps with energy efficient ones even before they burn out. So much energy may be saved that its value will soon offset the cost of the new lamps. And this is true even if your present standard lamps are relatively new since the life of a fluorescent is as much as 20,000 hours, it might take you 10 years to wear out a recently installed standard fluorescent during which time you would use extra electricity worth considerably more than the cost of a replacement lamp. If your fluorescents are used very infrequently, it may not pay to install the new energy efficient lamps until the old one have burned out.
Fluorescent lamp life is rated according to the number of operating hours per start, for example, 20,000 hours at three hours operation per start. The greater the number of hours operated per start, the greater the lamp life. Because fluorescent lamp life ratings have increased, however, the number of times you turn a lamp on or off has become less important. As a general rule, if a space is to be unoccupied for more than a few minutes, you should turn the lamps off.
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