Actually David, i havent had any problems with humidity on these lights. i lived in Florida for 14 years where the humidity is a constant 100%+ and the shoplights there never really had a problem with the moisture.
The bottom lights are protected from the top with a plastic cover between the lights and the plants above. ive actually found that the lights keep the humidity nice and high around the plants, but up around the lights, the warmth keeps the air a little more dry. ive got a fan running as well keeping it from condensating on the fixtures and for air flow. hope this helps
Happy growing
Kris