These devices ensure the connection of the lamp to the electric supply.

For incandescent lamps
Such devices are not required for incandescent lamps, except for very-low voltage tungsten halogen lamps which require a voltage converter. This is a device converting the voltage of the electric supply to the low voltage necessary to operate the light source.

For fluorescent lamps
In the case of fluorescent lamps, the connection is made through a ballast. This is a device connected between the supply and one or more fluorescent lamps which serves mainly to limit the current of the lamp(s) to the required value. A ballast may also include means of transforming the supply voltage, correcting the power factor and, either alone or in combination with a starting device, provide the necessary conditions for starting the lamp(s). They fall into two broad categories:

      Electromagnetic Ballasts for fluorescent lamps
      Electronic Ballasts for fluorescent lamps

Ballast losses depend on the lamp and the type of ballast. Several classes of ballasts have been defined by CELMA depending on the ballast-lamp circuit power, with different levels for each lamp power and ballast type. CELMA is the Federation of National Manufacturers Associations for Luminaires and Electrotechnical Components for Luminaires in the European Union.

For other discharge lamps
The other discharge lamps also need a ballast to operate. Here again, the electronic version offer several advantages compared to the conventional version: Lower consumption, eliminate flicker, cope with voltage variations, smaller size. Electronic ballasts are available for Metal Halide lamps (certain models), Low Pressure Sodium lamps and High Pressure Sodium Lamps (certain models).