Ballasts: 13 of 21

Inrush current is the surge of current that occurs when power is initially applied to a ballast. This surge may damage power switching components, such as light switches, relays, circuit breakers, and occupancy sensors unless it is taken into account in designing the system.

With electromagnetic ballasts, the inrush current is typically 10 to 20 times the steady state rms (root-mean-square) current of the ballast.

Electronic ballasts with passive input circuits (typically THD <20%) have inrush currents up to 30 times their rms current with duration measured in milliseconds.

Electronic ballasts with active input circuits (typically THD <10%) have inrush currents up to 100 times their rms current with duration measured in milliseconds.