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Not sure what that I can see that pic very clearly,but here's how mine(IOTA)(and most)work. The small handles in the pic go to mini-breakers. The form factor in this case is to save space - both of those breakers (in the pic a 15 and a 20) are in the same phase - if you look at the rear you will see only one attachment to the buss. The next adjacent pair of mini-breakers (if they exist) will be in the opposite phase and so on. If you use full size breakers then adjacent breakers will be out of phase with each other. Typically, these panels will be what a tradesman would call "back-fed". In this scenario the "feed" - probably a red and a black #6 type TW wire (part of a 6-3 with #10 ground piece of Romex (type NM) cable)anyway, the red wire will go to the bottom of a full-size 50A breaker and the black #6 will go to the bottom of an adjacent full size 50A breaker. This will feed voltage from the red #6, thru the breaker (limiting the current to 50A) to the buss feeding every other stab. The black will do the same to alternating stabs. Or black, red then black, red, etc. If you put an adapter on the end of your 50A cable to hook up to 30A then what happens is that there is an internal jumper built into that adapter (dog-bone). You will only have 1 30A hot wire from the pedestal but that jumper feeds voltage from that single hot source to both 50A breakers in your RV panel so everything in the RV will still work, BUT the total wattage available will be about 3600W versus the 11500W or so available with the 2-pole 50A source - result, you can't run as much load.
It is very important that if you hook up to a 50A source you make sure (read with voltmeter) that there is indeed 230-240 volts between phases - my pedestal, for example, was wired wrong when I checked it in Florida. What can happen, no, what will happen if both 50A hots are in the same phase is that you run a very real chance of overheating the neutral wire (white wire)in your panel. Extreme example - pedestal is wired wrong - both hots in same phase- and you have, say 35A on one phase and 45A on the other phase. Result: neutal caries 45 plus 35=80A which will overheat the neutal wire, possible causing a fire. Neither breaker will trip because the amperage is within the rating of the breaker and there is no current limiter on the neutral so . . . smoke city. On the other hand, if you have a 230 (out of phase) source you will still have the 2 50A feeds but, the neutral will carry 45 minus 35=10A, which is well within the rating of the neutral. What really happens here is that the neutral is a center-tap on one winding of a delta-connected transformer and carries the difference in current from both sides of the center tap. Or, as Richfaa pointed out, in a Y connected transformer you will have 208V and 117V at
the tap, versus 230 and 120 + or - a couple of volts. Most appliance with motors will tolerate around 8 to 10 percent below rating, so if voltage goes below 110 you are treading in dangerous territory in keeping your AC or any motorized device alive.
Phew, got more technical and long-winded than I meant to but, just be careful with those pedestals was my intent.
Jerry
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