How far should a 600HPS be from a young vegging plant in a 72" x 30" x 20" cab.

I have a plant in a 72" x 30" x 20" cab. The temperatures don't go above 85 but how far should I have the light from the plant? I have already moved the light positioning a couple of times because I can't quite tell if it's too much for the leaves to take.

This is my first grow.

you can do the hand test, put your hand in between the lights and plants. if its too hot for you....its too hot for the plants.


as long as the temp is keep in check....you can put it 8 inches if you wanted too....(air cooled light of course)

With my a/c hood, my plants can touch the glass with out burning from heat. They burn from too much light, but thats a different story.
If the plants are young, you don't want it too close. But that depends on how young exactly we are talking about. If the plants are fine at the height the light is at, lower it a few inches and see how they like it. If they are fine still, keep lowering it every day until they are too close. THen move it back up to the spot it was before it caused problems, and leave it there.