Depends on the LED lights you are using. I'm using 100 watts... The market is flooded with a lot of poor quality products. You should search some LED forums and figure out what suits your grow area/space/budget. Please read some of the links posted in my earlier posts they will answer the questions you seek. I don't have time/patience to double post information thats been mentioned elsewhere.
They don't get hot at all (the light has a heat sink on it, and its warm to touch), But i still run a fan for air circulation, because stagnant air is never ideal.
Let this also go out to those that will ask info to "help them purchase their LEDs" --- I'm not going partake/involve myself in that discussion, so please don't post asking me questions that you should look up yourself. I'm lazy.
Final note: If you have less that 5 posts made, please don't spam my grow journal with: ZOMG LEDS ARE AWESOME (or any bullshit of that sort). I'm not trying to establish my journal as a haven for noobies that just want to push LEDs because they are flamed on every post. Again, if you want to debate, take it elsewhere. I really want to have a RIU stress/drama free grow.