Light emission from gas discharge lamps without fluorescent materials is an almost inertia-free reproduction of the time response of alternating current (50 Hz mains frequency). Luminous flux pulsates at twice the mains frequency. Normally this 100 Hz flicker is not perceived by the human eye, but in the case of fast moving or rotating objects (e.g. a lathe) its can cause an optical illusion, creating the impression of slower or even reverse movement. Such situations can be dangerous.

Stroboscopic effects can be minimised or avoided through the use of a Dual Circuit, 3-phase wiring or electronic Ballasts.