When light bulbs were a new invention, a device was placed within the bulbs.They were called ballasts and controlled electricity flow(or called external driver). Today’s LED fixtures andLED light bulbsuse a driver to do the same thing, just at a much more precise level.
The purpose of the light ballast was to limit the amount of current in an electrical circuit. This device is known as a Ballast. If this was not used in the light bulbs or tube lights, there remained a risk of current rising to a destructive level. Ballast is still used in bulbs and tube lights to avoid current rise in the lights. Household light bulbs now use a mini transformer inside. Metal halide, mercury vapor, and HID are the prime examples of lights using external ballasts.
A ballast regulates the current to the lamps and provides sufficient voltage to start the lamps. It makes sure that the amount of current being provided to the lamp is not more than the specification of the light. Without a ballast, a lamp or a bulb will rapidly increase its current draw and it can become uncontrollable as well.
When a ballast is present in a lamp, the power becomes stable, and even if such lamps are connected to high power sources, the ballast will regulate the energy and avoid the current rise.
