Editing Fluorescent lamp (section)

===Ballast===
[[Image:Old USSR Ballast.JPG|thumb|Magnetic [[electrical ballast|ballasts]] have a low [[power factor]], when aren't connected to a power factor correction capacitor. This increases current drawn by the lighting fixture.]]
Fluorescent lamps require a [[electrical ballast|ballast]] to stabilize the current through the lamp, and to provide the initial striking voltage required to start the arc discharge. Often one ballast is shared between two or more lamps. Electromagnetic ballasts can produce an audible humming or buzzing noise. In North America, magnetic ballasts are usually filled with a [[tar]]-like potting compound to reduce emitted noise. Hum is eliminated in lamps with a high-frequency electronic ballast. Energy lost in magnetic ballasts is around 10% of lamp input power according to GE literature from 1978.<ref name=GE1978 /> Electronic ballasts reduce this loss.