I just had an electrician in to add some capacity to my room. Only a 100 amp service but he added 80 amps to my room with a "pony panel". I think that's what
@osowhom means when he says subpanel, right. I could have wired the subpanel 240 and used half the amps but all my equipment is 120 volt already and I grow in water so 240 is a bigger danger with pumps in reservoirs and such.
The first pic is the panel mounted below my cabinet that holds my 100 amp service. He ran the 12 gauge wire up the wall and out to the receptacles. It was easy because the panel is in my grow room. Second pic is a close up of the panel. There are four 20 amp breakers each attached to about 25 feet of 12 gauge wire with one 4 position receptacle box on the end of each run.
The third pic is a 600 watt HPS on a rain-tite intermatic timer plugged into one of the receptacles. The AC is plugged in and running on the same 20 amp circuit. The fourth pic is a close up of the same receptacle. I mounted it on a piece of 2x6 and used two 3 inch wood screws to attach the unit to a wall stud, but you can move them anywhere. After years of running extension cords; it's pretty cool.
I can post pics of the wiring if you're that brave, but I recommend finding a pro like I did.