Thank you for the detailed reply! I very much doubt I'm going to need more than 20 amps -- right now I'm planning an all-CFL scrog or sog as the first grow to test out the chamber, then maybe upgrading to 400-600 hps if everything else seems to work out okay.

As far as draw on the circuit, the attic fan appears to be burned out (also looks like it is 60 years old), so I was planning to just run my exhaust duct to the vent where the attic fan is currently installed. That means for my first grow I'm probably looking at no more than 300-ish watts of CFLs, plus an exhaust fan (still haven't decided what size), plus a new light fixture for the attic (which I will plug into my outlet). Even at the largest I can imagine going in the future, I'm looking at about half the wattage of HPS from your example, and no attic fan.

So should a 20 amp outlet suffice?
ourkansaw Reviewed by ourkansaw on . No electrical outlet... what's my best option? So I'm ready to get started with setting up a grow room in my attic, but right now I really only have one major hangup: electrical outlets. The attic has a 20 amp circuit dedicated to it, but no one has installed any outlets. There is a 12/3 NM-B cable that comes out of the insulation in the wall and goes to a switch box with two switches. One of them controls a light socket, the other controls a small fan that can be turned on to vent hot air out of the attic, both of which are along the Rating: 5