I honestly like your original idea better because it's simpler, cheaper & easier if you only want to run three 1000w rigs. The most you can do with a 30A feed is 5.
Once the main breaker in your panel is off, the only part that has power is where the power comes in from the pole, usually at the top. It's a very straightforward operation to swap the 30A breaker for a 20A. When you have the new breaker in your hand you'll understand how it mounts to the buss bars.
Having recently helped a friend wire a grow, I can say that what you want is either an Intermatic T103, T104 or GM40AV timer. 240v is really just two 120v feeds that are 180 degrees out of phase so you want to switch both of them using DPST (double pole single throw) contacts. Details-
http://www.intermatic.com/en/products/timeswitches/mechanicalswitches/24hour/t100series
http://www.intermatic.com/en/products/timeswitches/electromechanicalswitches/gm40avseries
You can use a T103 w/ 125v clock motor because you have a 4 wire 240v feed.
Although the electrical code specifies that the same gauge wire be used throughout the circuit, it's safe to use #12 from the timer to the receptacles having a 20A breaker. It's much easier to work than #10. Rives might disagree on principle. He's the real electrician.
Good quality receptacles-
http://www.westsidewholesale.com/le...gle_Shopping&gclid=COG-sIv_5skCFQ8taQod6gUP_Q
You'll need 240v ballast cords, like this-
http://www.joeshydro.com/240-volt-p...m=9JH-BPC140&gclid=CMzNs9iX58kCFQyPaQod8L4Ivw
The sources are just what I grabbed from google.
thanks again rives. you have cleared up a bunch of questions I had and im sure ill have some more if you don't mind me asking.
If you are running a new circuit, it doesn't make any difference which way you go. The controller is for 240v, and the neutral is unused. They probably make the connection optional to ease the installation if you have an existing 3- or 4-wire receptacle.
A GFCI might save you from doing the 60-cycle shuffle if you have a grounding issue with one of your hoods.
Just so you know, I haven't had one apart to verify it, but the information from Powerbox doesn't show any additional fusing to protect the 15a receptacles and downstream devices that will be fed with up to 30 amps.
So I'm gonna be hooking up a powerbox dpc-4000. It has 2 available configs. 3 wire (2 hots + neutral) or 4 wire (2 hots, neutral, and ground). Have to install a 30a double pole breaker and run some wire from my panel. What would you guys recommend...3 or 4 wire? Gonna go with 10ga wire. Also...do I need a gfci breaker or just regular? The only thing being plugged into this line is my powerbox
Can i run a T104 with 12/2 wire from a 20 amp breaker? The lights are 240v for a total of 9 amps but timer is rated at 40 amps.