Bill Tindall, E.Tn.
advice to self: don't send a post in a hurry
"What is the "lumen" output of the LED lamp or fixture? Typical T8's are in the range of 2900-3100 lumens per lamp, so a 4x4' toffer yields about 1200 lumens"
The correct data are:
A 2 x 4 T-8 Troffer fixture (4-lamps) will produce about 12,000 lumens. It took 3 of these over my bench to get 200 foot candles of illumination at the bench surface. All this overhead acreage was replaced with 2- 4 lamp T5HO units that produce 20,000 lumens each.