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Technologies > HIGH-EFFICIENCY ELECTRONIC BALLASTS
The result is lighting system savings of typically 2-5 watts per ballast. According to one manufacturer, using high-efficiency ballasts can save the owner about $1 per lamp per year. For example, a standard two-lamp T8 ballast with 0.77 ballast factor operates at 51W while the high-efficiency ballast operates at 47W. High-efficiency ballasts are popular for retrofits because they provide equivalent light levels to installed F34T12 systems. High-efficiency ballasts are ideally suited for use with 25W, 28W and 30W energy-saving T8 lamps and high-lumen T8 lamps. These combinations can reduce system watts by over 45 percent compared to older T12 systems (see Table 1), and 20-30 percent compared to standard T8 systems (see Table 2). Characteristics: The ballast may be instant-start or programmed-start, and available with low, normal or high ballast factor options for different levels of light output and subsequent application flexibility.
In addition to energy savings, high-efficiency ballasts offer a range of features such as anti-striation and anti-arcing, which enhance safety and reduce maintenance concerns. Additionally, many high-efficiency ballasts are available with universal input voltage to simplify stocking requirements and installation. Universal-voltage ballasts virtually “read” the incoming voltage and adapt automatically for any voltage in a wide range that includes standard voltages 120V and 277V. This means fewer ballast models can handle a greater number of applications, reducing inventory requirements; the ballast compensates for incoming voltage fluctuations or variations from unreliable power; and installation becomes simplified because contractors don’t need to bring both 120V and 277V ballasts to the jobsite. Applications: High-efficiency ballasts can be used in any general fluorescent lighting application, such as office buildings, schools, libraries and hospitals. Applications with high utility rates or long operating hours are particularly suitable. High-efficiency systems are also used in high-bay fixtures for replacement of HID systems. The only limitation is residential applications, due to FCC ratings.
* Net system lumens per watt = (mean lumens X number of lamps X ballast factor) / input watts Table 2. Upgrade opportunities: System performance/savings on new T8 options vs. standard 4-lamp 277V T8 system. Source: Advance.
* Net system lumens per watt = (mean lumens X number of lamps X ballast factor) / input watts
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Description: A high-efficiency electronic ballast is often described as one that provides the same level of light output as a similar standard electronic ballast, but does so more efficiently. Another definition of a high-efficiency ballast is one that has a higher ballast efficacy factor (BEF) than a similar standard electronic ballast. (BEF is calculated as ballast factor divided by input watts x 100.) 
High-efficiency programmed-start ballasts are a recent introduction. Some manufacturers now offer high-efficiency programmed-start ballasts that offer the same efficiency as standard instant-start ballasts, which make them much more competitive. Programmed-start operation reduces wear and tear on the lamp during startup, which maximizes lamp life. These ballasts are highly suitable for applications where the lighting is frequently switched, such as spaces using occupancy sensors.
Disadvantages: High-efficiency ballasts have no limitations compared to standard electronic ballasts, but typically cost 10-20 percent more. In an installation with two-ballasted four-lamp fluorescent fixtures on 10x10 centers (100 sq.ft. area), this can translate to an added cost of about 3-6 cents per sq.ft.—while reducing annual operating costs by about 4 cents per sq.ft., based on an assumption of savings of $1 per lamp per year. With lamps and ballasts representing only four percent of the total cost of light, despite their higher cost, high-efficiency ballasts typically improve the payback of a lighting retrofit.