A 15 watt 18 inch t8 tld fluorescent triphosphor tube this t8 fluorescent tubelamp has an average life of 15 000 hours and has an a class energy efficiency rating t8 fluorescent tubes are available in colours standard white 835 cool white 840 boxed in 25s general characteristics wattage w 15 initial lumens at 25degc lm 1000 capbase g13 lamp diameter mm 26 lamp length mm 4516 colour temperature k 2700300035004000 colour rendering index cri ra 85 avera