MH ballast question...
 

I have noticed you can get some MH ballasts mounted in a box. Are there any advantages or disadvantages to having one ballast or two ballasts mounted in the same box. Im wondering specifically about the heat issue. Will the ballasts stay cooler and run better/longer if housed only one to a box?

Im thinking of the 250W PFO HQI ballasts. Any input is welcomed...

I don't think it makes much difference except for price. One case is theoretically half as expensive as two cases.

Right. I have 2 in one box, a single in another box, no better or worse either way, cost of boxes goes down with two ballasts in it!