All fluorescent lamps must have a supplementary component, commonly known as a ballast, to limit the current and to provide the necessary starting voltages.

Each ballast is specifically designed for its operating service voltage and other characteristics.

2-lamp ballasts are either lead-lag or series-sequence design. In the lead-lag variety, each lamp operates on its own independent circuit one leads and the other lags. This provides a high power factor (between 90 and 100%) and practically eliminates all stroboscopic effects.

In the popular series-sequence design, the lamps start in sequence and when fully lighted operate in series. These ballasts also operate at high power factor but don't correct for stroboscopic effect.