The rated CFL life as claimed by manufacturers is based on 3-hour-on/ 20- minutes- off cycle of operation. In actual applications, the CFLs are switched on and off at different rates and under different climatic conditions. Therefore the actual life of CFL is different than the rated or predicted life. If CFLs are started more frequently than the standard 3-hour on/ 20-minute off i.e. shorter cycles operation- they will have statistically shorter life than their rated life.
http://rtf.nwcouncil.org/meetings/2009/05/CFLCyclingImpacts_PhysicalBackground.pdf
