Commercial fluorescent lighting systems consist primarily of T8 lamps and electronic ballasts. While LED linear tubes now compete as replacements for traditional fluorescent, the vast majority of existing and replacement ceiling lighting in offices, schools, hospitals, and other institutions is fluorescent. At it's best, fluorescent lamp/ballast systems can offer efficiencies, lamp life and cost effectiveness that rival LED.
A key feature of fluorescent lighting is the type of lamp starting technology used. There are three approaches: Instant Start, Rapid Start and Programmed Start. It's important for buyers to know the difference.
The operation of a fluorescent lamp depends of the actuation of a discharge between cathodes that are located at both ends of the bulb and the ionization of mercury gas within the tube.
This process involves two conditions, the cathodes must be heated to emission temperature and sufficient voltage needs to exist across the bulb to ionize the gas. How these two conditions are achieved defines the different lamp starting options.
Instant start ballasts work by applying a high enough initial voltage across the lamp to strike the arc. The cathodes are not pre-heated. As the name implies, the lamps are jolted to full illumination very quickly. This approach is best for applications where there is not frequent on/off cycling of the light switch. Instant start ballasts offer the highest efficiency among the types of ballasts for fluorescent applications. Because no energy is used to heat up electrodes, instant start ballast systems typically use 1.5W to 2.0W less energy per lamp than the rapid start option. Lamp wiring is parallel so if one lamp fails the others on the circuit remain lit.
Pros / Cons:
- Instant Start ballasts consume less energy than other ballast types.
- Instant Start ballasts result in shorter lamp life if used in applications with frequent on/off switching.
Rapid start ballasts start the lamps by applying voltage simultaneously to the cathodes and across the lamp. As the cathodes heat up, the voltage required to ignite the lamp is reduced. Because rapid start technology does not "shock" the lamps like instant start, this approach is somewhat better suited to applications with frequent on/off switching. Lamp life is extended, but the trade-off is increased energy consumption for rapid start systems. Lamps in rapid start ballast applications are usually wired in series. If one lamp fails, all other lamps on the circuit will not produce light.
Pros / Cons:
- Rapid Start ballasts provide the coil heating required to get the longest life out of the lamps in typical operating cycles of 12 hrs./day.
- Additional coil heat circuitry dictates an added cost for the rapid start option
Programmed start is a newer, more sophisticated version of rapid start. The voltage application sequences on the cathodes and across the lamp reduce the impact on the components of the lamp to a minimum. This starting method dramatically lowers the lamp stress of frequent on/off switching. Programmed lamp/ballast systems offer maximum lamp life in compared to instant and rapid start in frequent starting conditions (up to 50,000 starts). These ballasts also optimize the efficiencies expected from T8 lamps. Lamp wiring is typically in series.
Pros / Cons:
- Programmed Start ballasts provide maximum lamp life in frequent ON/OFF switching conditions.
- Programmed Start ballasts reduce lamp maintenance costs