Electronic Ballasts for more information on electronic ballasts. Although preheat ballasts are becoming outdated, they are relatively inexpensive. Some kinds of luminaires, particularly task lights, have preheat ballasts built into them. Rapid-start ballasts heat the lamp's electrodes before starting the lamp, and usually continue to heat the electrodes while the lamp is operating. Lamp life may be longer than with an instant-start ballast.
Many electronic ballasts use the instant-start method.
With this method, the lamp's electrodes are not heated prior to starting so a higher initial voltage is required to start the lamp. Specifiers should check with the manufacturer to determine if the ballast has a shut-off circuit. Lamp manufacturers claim that many T5FT lamps will also operate on alternative ballast types. However, ballast type can affect lamp power, light output, efficacy and lamp life. The T8 and T12 lamps are RE70 rare-earth phosphor lamps.