That's pretty much what I did with my setup. I've got the 60A dual-pole installed in my main panel. I ran #6 wire (rated for 75A) from that breaker to an 8 slot sub-panel in the grow room. From that sub-panel, I've run all the wiring for the room.
The difference is I use 220V for my HID lights. I've got two 600W lamps on one 220V ckt, one 1000W lamp on another 220V ckt, plus two 110V circuits for pumps, fans, etc. That leaves me with two blank slots for future expansion.
Two 1000W lamps on 220V will pull about 9.5A, while only one 1000W lamp on 110V will pull the same amount of current. The advantage is only having to run one 220V circuit instead of two circuits for 110V usage.
If you choose to run your lamps on 110V, make sure the circuits are on different poles so as to not pull lots of current through one leg, while hardly anything on the other.
Yeah, although I'm not an electrician, I've got lots of experience with wiring. My house had knob & tube wiring when I moved in. An electrician estimated $25k to rewire the whole house. The building codes say I cannot rewire my own house without a license, but I am allowed to run a circuit. So, one circuit at a time, I rewired my house. I did hire a pro to take out the fuse box and put in a breaker box, but that required pulling the meter so I didn't have much choice. I suppose I could have live wired it, but I didn't want to end up
U must "bond" the neutral to the panel w tha screw or ur neutral has path to dissapate unbalanced currents...and I AM an electrican!! And mad props mr.bill on ur diy homeowner skills!!....and always hire pros 4 pullin meters its 125amps @ 220volts at themetersockets...0.5 amps will kill u