I've decided I really do need a HPS on my next grow (after seeing how pitiful the yield is on flouros). I was just wondering about heat. My grow area is just thick fabric stapled to the cieling, it's lightproof so it works for me. I worry about fire... If the ballast of a 150w is 6 inches away from a heavy fabric will it burn? Also at what point is it necessary for the ballast to have a porcelin socket? Will a 150w require it? I suppose I would have gotten one for this grow, but I'm growing in my parents house so I really don't want to burn it down.
The ballast of a 150w HPS wouldn't create nearly enough heat to burn the cloth. There usually isn't a great danger of fire until you get into the mass-scale grows. My 250w HPS produces just enough heat to keep the growroom warm, but not hot. As far as the socket, I'd just get a good quality one now, to prevent hassle and/or problems in the future. ~Ly
My 400W HPS can bring the temperature up to 40 degree's celcius on warm days. It's quite sad, but that's because I have very little means of ventilation.