List Of T8 Vs T12 Fluorescent Light Fixtures References. All fluorescent lamps need ballasts to maintain the current passing through the lamp at a certain value. The narrower your choice of a fluorescent lamp is, the more efficient its energy output will be.

T8 fluorescent bulbs also have a lower cost per watt of output. All fluorescent lamps need ballasts to maintain the current passing through the lamp at a certain value. Web the luminous efficacy of t5 lamps is about 100 lm/w, while those of t8 and t12 lamps are only about 80 lm/w and 70 lm/w respectively.