Fluorescent tubes, as well as all other types of gas discharge lamps, are not suitable for direct connection to the electricity grid. Ballasts are used for current limit and in combination with starters, also for ignition of lamps. Conventional fluorescent and gas discharge lamps do not work without a ballast and must therefore always be connected to it. For fluorescent tubes we are using currently in the 3rd generation of ballasts and even with LED you need “ballasts” again, which are referred to as drivers.



In general, there are two types of ballasts


  • Conventional ballasts and also the low-loss version of it
  • Electronic ballasts





Conventional ballasts



Since 2017, only ballasts with energy class A2 or better are being installed! In the following years, conventional ballasts are unlikely to be sold in the EU as they do not meet the increasing energy efficiency requirements. These devices will suffer a similar fate as incandescent bulbs, since the use of electronic ballasts is more efficient.


Starter

The conventional ballast consists of a coil. In simple terms, this coil ensures that the fluorescent tube is supplied with an operating voltage of 50V - 100V. Conventional ballasts for fluorescent tubes also require additionally a starter, which preheats the tube (both ends then glow orange). Afterwards the current flow is interrupted for a short moment, creating a voltage spike of about 1000V in the coil. As a result, the gas in the tube will glow. Starters cause the characteristic flicker of fluorescent lamps at startup.



Note: You should always replace the starter with the lamp. It usually does not last longer. A low-loss ballast is basically the same as a conventional, only a little more efficient.


Electronic ballasts



The current technology is the electronic ballast. Electronic ballasts start and operate T8 or T5 fluorescent tubes and discharge lamps in a significantly different way than conventional ballasts. They work without a starter and regulate the ignition pulse through the integrated electronics. Inside a high voltage is generated through coils and capacitors, causing the gas to light up.



These ballasts are significantly better than the conventional ones:


  • Higher lifetime for the lamps
  • Better efficiency
  • Fast lighting power and flicker free
  • Dimmable and equipped with DALI


Electronic ballasts can also be integrated in light sources, such as compact discharge lamps (energy-saving lamps) with screw sockets (E14, E27) - or as part of the fixture!


LED driver



Starter

LEDs also work with an electronic ballast, the so called LED drivers. LEDs are very sensitive to current fluctuations and can be easily damaged. The drivers guarantee a constant output, even over a wide voltage range, so the LED is constantly operated with the ideal current value.



Note: For more detailed information regarding the drivers for LED tubes, please read our following blog posts about ‘The differences between the single Osram and Philips LED tubes’.