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comment on lumens
Jim Spencer suggested that, "A better choice might be the Sylvania
Designer 865 lamps. These are daylight lamps that have a much higher
initial lumen output than the
sunshine lamp( 3100 vs 2250 for the 40W lamps)."
Keep in mind that lumen measurements are weighted towards the part of
the spectrum that the human eye sees, and not necessarily what the
If you look at the lighting system (lamp and ballast) as a closed
system, all the electrical energy going into the system leaves the
system as heat or light. Assuming you have the same ballast and are
comparing two lamps with the same wattage rating, the light energy that
leaves the system has to be equal for both lamps, right?
Jim also mentioned, "Because they have a long life and a very good lumen
maintaince they may be cheaper in the long run." This is a good point
to think about. For example, 4' F40 T12 cool whites have less than 80%
of their initial lumens at 100% of their rated life. Standard 32 watt
T8s maintain about 85% or so of their initial lumens. GE's new T8s
maintain 95% of their initial lumens. And all of these lamps have a
rated life of 20,000 hours.