For a lot of us, ballasts (i.e. Metal Halide Ballast) are a mystery. All distribution systems of Electrical output have fixed AC voltage (50 or 60 Hz) and should expect connected electrical loads to limit the current drawn from the power source. Metal Halide Bulbs and High Pressure Bulbs arc discharge lamps exhibit “negative impedance.” if you don’t have a ballast, the arc in the bulb will extinguish or draw increasing current until some circuit element burns up (reducing life considerably).

Ballasts provide bulb stability by regulating the current that can be drawn from the power source. Ballasts use inductive and capacitive parts because they impede AC with very little power consumption. Resistive parts generate high loss and are usually avoided. This is true of all normal electromagnetic ballasts as well as all electronic ballasts. (i.e. T8 Ballast)

HID ballasts are needed for the following functions:

• Provide voltage to breakdown the gas within the light bulb (i.e. Grow Bulbs) and the electrodes of arc within the lamp and initiate starting.

• Provide the correct voltage and the correct current and will heat the electrodes to allow a low voltage, high current arc scenario to develop.

• Maintain the arc during warm-up and operation continue the operation of the bulb.