When I made my grow room sub panel box.. I ran from a double pole 50 amp 240 breaker in the main panel that is outside out to it (via RV plug and cord), and then simply split it in half into 4 120v circuits at the sub panel (4 breakers, 15/15/20/20 in a 70 amp load center box). There are 2 hot wires in my main power cord running to the box, so just separated them by plugging in 120 breakers on each side of the box, instead of putting one double pole 240 back into both, which I could do If I wanted, but takes all the slots.
The circuits all share the same oversized neutral wire, because I ran a 4-wire 30 ft RV extension cord (that cost almost as much as a lighting controller these days lol) into it. All flexible stranded wire inside, 8 ga I think, and is outdoor rated too, sitting right on the ground for years now with no problem. Super nice camco cord! As far as I knew, you Just have to be careful spreading the loads around so you don't mess with the phases (i could be wrong on that) and cause an imbalance, or something I'm not too sure about, other than it works lol. I just know both sides share the same neutral, and you don't want to create multiple paths, and it needed to be bonded at the main but isolated at the sub box if I remember right.. with a bonding screw that either is in or out, depending on the configuration. Also I was right next to the main, so didn't need to run an extra ground rod or anything, I hope
So technically, I have like 2 x 50 amps worth of 120v energy (up to 12,000 watts or more?), all for my little grow trailer, and only use like 2-3 lights worth. 20 amps at the most usually, unless I'm at full perpetual operation, and depending on the season.
I'm hooked up just like at the RV park with 50 amp service, and my even cord wraps up and stores under the RV grow trailer incase I needed to move it somewhere else.. Might say its overkill, but I also run my greenhouse that is next to the trailer sometimes (they work together at times), and can hook up anything I want. Chillers, mini splits, heaters, dehuey's, welders, and even run high amperage power tools to work on more grow rooms and equipment while I grow..
There is always this nagging feeling I have though, that by splitting the wires like that, and sharing a neutral wire i'm screwing with the current in some way, but everything works so I don't trip, and neither has the main breaker ever.
My electrician uncle came out and wanted me to bury lines and whatnot, but I didn't take his advice, and did it my own unqualified way. Why would I bury a 3 wire line to a mobile trailer I thought?
