danny burstein wrote:

My head hurts on trying to figure out just how a legacy
ballast can worh with a retrofitted LED tube, but
they do. I've installed a few of them.

I only yesterday figured out how (by looking it up) a legacy ballast works
with LED tubes, but I couldn't find an article that explains how it works
with LEDs.

I measured the before and after using a Kil-a-watt brand meter.
Don't have the paper here, but the measurements were something
like the following.

twin "40" fluorescent fixtu

Ballast only w/no lamps: 12 watts
Ballast w/both lamps: 84

Retrofitted with a "drop in" LED:

Ballst w/LEDs: 60

Light output was higer with the LEDs.

Again, these are NOT the exact numbers,
but there definitely was a savings when
using the drop in replacements.

Thanks for providing that reference information.
I have to admit, the two 4-bulb lamps currently with the LEDs in them are
brighter than the sun it seems, at least in a garage they are.

Compared to the fluorescents, they rock with light output!

I just hope they last, given they are T8s on a T12 ballast.