Installing efficient ballasts can reduce energy consumption while maintaining existing light levels. However, ballasts are often the most expensive first-cost component of a lighting retrofit. Fluorescent lamp ballasts typically cost between $10 and $50, but ballasts for high-power lamps, such as T12/VHO (very high output) lamps and some dimming electronic ballasts, can cost considerably more. Fortunately, there are generally substantial discounts for the purchase of the large number of ballasts needed for new construction or renovation.
The best choices for ballasts are listed below.
Electronic ballasts. Electronic ballasts are about 10 percent more efficient than conventional line-frequency magnetic ballasts. They eliminate flicker and hum and are extremely cost-effective. Although electronic ballasts are almost always the best choice, they may not be appropriate for applications with very high temperatures or for equipment that is sensitive to the high-frequency electromagnetic interference generated by some electronic ballast/lamp systems. It is still best to use magnetic ballasts in certain situations, such as in recording studios, near radio-frequency security systems (such as those in bookstores), in extremely hot or cold conditions, or in other particularly sensitive electronic environments. Although the DOE ballast rule effectively eliminates most magnetic ballasts used with T12 lamps, magnetic ballasts should still be available for T8 lamps in these niche markets.
High-performance electronic ballasts. The most efficient fluorescent ballasts are the high-performance electronic units that comply with the Consortium for Energy Efficiency's (CEE's) lamp and ballast specifications (Table 1). The National Electrical Manufacturers Association (NEMA) Premium Ballast program adopted the CEE's specifications and places its “NEMA Premium” stamp on the ballast label to eliminate confusion caused by manufacturers who were mislabeling standard ballasts as high performance. High-performance ballasts used with high-performance lamps are typically the most efficient solution with the lowest life-cycle cost. They are a good choice where color quality is important, such as in high-end retail spaces, the hospitality industry, healthcare facilities, and schools.
Table 1: High-performance T8 ballasts
According to the specification from the Consortium for Energy Efficiency, high-performance T8 ballasts must have a ballast efficacy factor (BEF) at least as high as the ones shown here.
Instant-start ballasts. This is the most efficient type of ballast, but it yields the shortest lamp life in applications with run times that are shorter than three hours. It is a good choice for lamps that burn six hours or more per start.
Programmed-start or programmed rapid-start ballasts. This is the best choice in applications where lights will frequently be turned on and off. They are the improved versions of the older rapid-start technology that maximizes lamp life in almost all cases—although there is some penalty in efficiency.
Universal-voltage ballasts. These ballasts typically accept any input voltage between 120 and 277 volts. They make retrofitting easier and reduce stocking requirements, but they are slightly less efficient than dedicated-voltage ballasts.
Dimming ballasts. Although they cost more and are less efficient at full power than their nondimming counterparts, dimming ballasts provide useful benefits. For example, fully dimmable fluorescent ballasts can be set for such functions as automatic daylight dimming, lumen maintenance (automatically adjusting ballast power to compensate for the gradual loss of light output over time that all fluorescent lamps experience), occupancy-controlled and -scheduled dimming, and manual-task dimming (whereby the occupant uses a rotary or sliding dimmer switch or computer control). Several dozen models of continuously dimming ballasts for full-size fluorescent lamps are now available in the US, and prices are dropping into the low-$60 range for one-lamp dimming ballasts.
Finally, check with manufacturers to make sure that lamps and ballasts are compatible. Most lamps are only compatible with one starting method; the major exceptions are high-performance T8s, which can use either rapid- or instant-start ballasts. If you operate a lamp on an incompatible ballast, the lamp may not start, or it may operate at an abnormal output level, which will greatly reduce lamp life.