![cover image](https://wikiwandv2-19431.kxcdn.com/_next/image?url=https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Fulham_Workhorse_4_ballast.jpg/640px-Fulham_Workhorse_4_ballast.jpg&w=640&q=50)
Electrical ballast
Device to limit the current in lamps / From Wikipedia, the free encyclopedia
For other uses, see Ballast (disambiguation).
An electrical ballast is a device placed in series with a load to limit the amount of current in an electrical circuit.
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/Fulham_Workhorse_4_ballast.jpg/640px-Fulham_Workhorse_4_ballast.jpg)
![Thumb image](http://upload.wikimedia.org/wikipedia/commons/thumb/8/80/LAjaHID.jpg/640px-LAjaHID.jpg)
A familiar and widely used example is the inductive ballast used in fluorescent lamps to limit the current through the tube, which would otherwise rise to a destructive level due to the negative differential resistance of the tube's voltage-current characteristic.
Ballasts vary greatly in complexity. They may be as simple as a resistor, inductor, or capacitor (or a combination of these) wired in series with the lamp; or as complex as the electronic ballasts used in compact fluorescent lamps (CFLs).