Olyver that all depends on what you are trying to do.
Flip boxes are designed to use 1 ballast for 2 different lamps. When lamp #1 is on #2 is off, then the timer provides the switch signal and #1 goes off and #2 goes on. In this manner you can use 1 ballast to control 2 lights in different rooms/tents on an alternating basis and the ballast never needs to be switched off relieving you of the need of a loadcenter which is nothing more than a relay box to turn ballasts off and on.
I think I know what a flip box is designed to do. The loadcenter is to power off the ballasts every 12 hours for a cold flip. Those are not flips, this is a flip..... These flips use 1 relay (30A) for 1 ballast and 2 lights, horticontrol uses 1 relay (10A) for 2 ballasts and 4 lights, it is unsafe and electrical inspectors in Canada won't allow them in HC designated gardens.
The load on the relays at the time they are opening or closing is zero. The ballasts are off when the relay is triggered to open or close. How could 10A be deficient for this purpose? The conductors in the ballast cord are 16ga.... and they aren't energized at the time.
To the OP, these don't connect to your dryer outlet homie. The only incoming power on these is the relay trigger which you plug into a standard 120v 15A outlet. The relays inside switch the ballast output cord when not energized and they are safe. Lots of people use these. That's crazy about CA not allowing them. I'm interested to know why. You need a relay to power the actual ballasts to that will take 240v in from the dryer outlet and power the outlets you'll plug your ballasts into. Get the one that has a timer built into it and you'll need a second time for the flip. Have the ballasts kick off about 5 minutes before the flip kicks over and have them stay off for 5 minutes after so you know they are for sure off when the flip kicks over.
You first need a lighting controller and timer to power your lights. The lighting controller is what plugs into the dryer outlet.
Then your flip box comes with a bunch of plugs that will plug into your ballasts. Now that your ballasts are connected to the flip boxes, you simply plug your light fixtures into the flip box.
The flip box will have 2 banks. When the timer is on, 1 bank is on. When the timer is off, the other bank is on. Your lighting controller timer will always be on.
There are many many ways to do this, but it all depends on your personal capabilities. Do you need to hire someone to do this for you? Are you trying to save money? Do you want to spend the time to find the most cost effective options?
I would just call Powerbox and ask for Jeff. Buy what he tells you to buy and call it a day.
Canada does not allow horticontrol flips because the neutral is not switched, instead all three neutrals are wirenutted together, and since the ballast is 240V, the neutral from the 240V power is spliced to the two neutral wires from the lampcords. There is a specific section of CEC that states that is not permitted, I posted it another thread, I will find and repost if neccesary. The hot and neutral must be switched.