... bulb, HID bulbs work by using a high voltage spark to ignite xenon gas. A ballast unit is ... 20,000 volts, which arcs between two electrodes, this spark activates the xenon gas, which in turn activates the ... , HID bulbs work by using a high voltage spark to ignite xenon gas. A ballast unit is ... 20,000 volts, which arcs between two electrodes, this spark activates the xenon gas, which in turn activates the ...