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[9] [10] The ballast factor of practical ballasts must be considered in lighting design; a low ballast factor may save energy, but will produce less light and short the lamp life. With fluorescent lamps, ballast factor can vary from the reference value of 1.0.
T5 retrofit conversion can maintain existing lighting levels with the higher efficiency of the T5 lamp. However, with kits that operates the lamp on the existing magnetic ballast, the efficiency drops and the lamp life is considerably shortened, as T5 lamps aren't designed to be operated on mains frequency but only on high frequency.
Running an energy-saving T8 tube with a ballast for T12 will reduce lamp life and can increase energy consumption. [9] Conversely, a T12 tube on a T8 ballast will usually draw too much power and so may burn out the ballast, unless it is within the range that particular ballast can compensate for.
Most modern ballasts are now also equipped with a dimmer, which uses pulse-width modulation to dim the lamp up to 50%, or as much as one stop of light. Unlike a tungsten-based light, which has a negative color temperature shift with a drop in power, the mercury emission spectra takes over with a drop in power (approximately 200 K bluer at 50% ...
Replacement of magnetic ballasts with electronic ballasts has removed most of the flickering and slow starting traditionally associated with fluorescent lighting, and has allowed the development of smaller lamps directly interchangeable with more sizes of incandescent light bulb. Electronic ballasts contain a small circuit board with a bridge ...
A quick-start ballast eliminates the need for a starter switch, a common source of lamp failures. Nonetheless, Quick-start ballasts are also used in domestic (residential) installations because of the desirable feature that a Quick-start ballast light turns on nearly immediately after power is applied (when a switch is turned on).
More sophisticated ballast designs detect cycling and give up attempting to start the lamp after a few cycles. If power is removed and reapplied, the ballast will make a new series of startup attempts. Another phenomenon associated with HID lamp wear and aging is discoloration of the emitted light beam ("fading" [14]). Commonly, a shift towards ...
There are also self-ballasted mercury-vapor lamps available. These lamps use a tungsten filament in series with the arc tube both to act as a resistive ballast and add full spectrum light to that of the arc tube. Self-ballasted mercury-vapor lamps can be screwed into a standard incandescent light socket supplied with the proper voltage.