How to Use Ballasts Correctly

New standards will eliminate most of the less efficient magnetic ballast designs by 2005

If you want to improve lighting system efficiency, ballast selection is critical. Today's most popular energy-efficient lighting designs involve new ballasts. Because ballast technology is constantly changing and improving, there are more choices now than ever.

Many people often make the mistake of choosing electronic ballasts with the lowest input watts rating for fluorescent lighting systems. This may result in increased energy savings, but it can also lower ballast factor (BF) and produce inadequate lighting. You can improve lighting levels by specifying BF based on the light level required for the space you're lighting.

You'll get the best results when you carefully consider ballasts for each application. Many retrofit projects have gone wrong because of improper ballast selection. Because they have advantages over more traditional solutions, new ballast designs may be the better choice for some jobs.

New-generation ballast designs can reduce the number of models that organizations must stock and help you avoid confusion over which ballast belongs in which fixture.

When working with older ballast designs, specifiers and designers had to carefully match ballasts to the lamps for which they were designed. If they weren't careful, lamp performance and lamp life usually suffered. Previous designs would often compromise the requirements of at least one lamp type.

The development of new-generation ballasts will eliminate the need to match lamps and ballasts. Some new models use microprocessors to apply the exact program for the lamps that are connected. They can sense both the lamp type and quantity and configure operating characteristics to provide the required lamp starting and operating parameters.

Many new ballast designs feature universal voltage capability — allowing input voltages from 100V to 300V. Others have high fault tolerances and shut off lamp current when they detect a loose lamp wire or end-of-life (EOL).

The new global standard for ballast size has dropped to 30 mm × 30 mm for the cross section (1.18 in.). As a result, ballast designs for both compact fluorescent lamps (CFLs) and linear fluorescent lamps are becoming smaller and lighter. Fixture manufacturers are incorporating these designs into new products and new models of slim-profile indirect and direct-indirect fixtures.

The efficiency of electronic fluorescent ballasts has also improved. Many facilities have installed instant-start ballasts, in spite of the negative effect they have on lamp life. In promoting the use of instant-start ballasts, one manufacturer claims the energy savings of 1.5W per lamp more than compensates for the difference in lamp life. This manufacturer estimates it would take 35 years to pay back the savings.

Program-start type ballasts, which provide optimum starting conditions, can provide as many as 100,000 starts, and the lamps last 50% longer. This design applies cathode heat for a precise time prior to lamp ignition and then removes it once the lamp has ignited. At least one manufacturer provides a program-start ballast for T5 HO lamps.

The higher efficiency of these ballasts, coupled with the lower maintenance costs, make them an ideal alternative to rapid-start models for switching applications. Some electrical professionals predict program-start models will replace rapid-start models in a few years because their longer lamp life cuts down on replacement costs.

All fluorescent lamp ballasts manufactured for commercial and industrial use in new and renovation markets must meet new, stringent standards of efficiency agreed upon by the U.S. Department of Energy (DOE), ballast and lamp manufacturers, and other stakeholders such as environmental organizations and the American Council for an Energy Efficient Economy. These new standards will eliminate most of the less efficient magnetic ballasts by 2005.

Most of the new miniaturized, electronic compact fluorescent (CFL) ballasts are designed for higher-wattage rapid-start (4-pin) CFLs with power ratings of 26W, 32W, or 42W. One manufacturer recently introduced a ballast that operates one 42W, one 32W, one 26W, or two 26W CFLs. They operate the lamps above 42kHz to avoid interfering with infrared remote controls, and they are available with high power factor and high BF (0.95). Most feature THD of less than 20% and carry 5-yr warranties.

These new ballasts are showing up as OEM packages for downlights and sconces, but end-users can also buy them for retrofit applications. They feature EOL protection circuitry, and the lamps automatically relight when replaced.

Advances in HID ballasts have also addressed the unique characteristics of pulse-start (PS) metal-halide lamps. PS lamps do not have a starter electrode, and they do not require the ballast to provide the peaking voltage necessary for older standard MH lamps. Therefore, these lighting system designs have lower current crest factors, which translates into better lumen maintenance and longer lamp life. Electronic ballasts are also available for most PS MH lamps. The major benefit of this design is lamp current control, which creates a more stable lamp operation. Stable operation can reduce color variations in lighting systems that must tolerate wide fluctuations in line voltage.

When relighting and upgrading lighting systems, remember that ballast selection is important in improving energy savings and improving lighting quality. Understanding the advantages of different ballast designs can help you choose the appropriate ballast for your needs.

Fetters is president of Effective Lighting Solutions, Columbus, Ohio.