Rapid Start
Instant Start
RS
IS
Coil heating provided so 2 wires connected to each end of fluorescent lamp. No coil heating so only 1 wire connected to each end of fluorescent lamp. However, the two leads of the lamp need to be shunted (connected).
Older ballast type, still needed for dimming systems and in situations where lamps are turned on and off frequently Newer ballast type, saves energy over rapid-start ballasts but in some lamps, lamp life may be affected slightly (e.g. 20,000 hours vs. 24,000 hours). However, most of GE's T8 lamps have been redesigned to provide the same life on IS ballasts as they had on RS ballasts.
Starts almost instantly (~ 1 second) Starts instantly