Originally Posted by OldCoot
You only use 1 leg of the 50 amp when you use a 50-30 adaptor.
Originally Posted by Tom48
You might have 50 but your onboard panel is only breakered and wired for 30. So 30 is your limit. Just might not blow the 50 amp pole breaker. The load will shift to YOUR breaker box.
Using one leg of a 50 amp outlet, still can allow up to 50 amps from the campground outlet, thru your power cord, to your electrical distribution panel inside the RV.
From the distribution panel forward, all of your circuits are "hopefully" protected by the RV's main 30 amp breaker.
As Tom said, if you overload the RV's circuit(s), then you hope the RV main 30 amp will trip.......since from that point back to campground pedestal will be 50 amp capable and will not trip the campground pedestal when you go over 30 amps and under 50 amps.
Your RV cord is going to be the weak link here. It's rated for 30 amps still. Normally it would be protected by the campground pedestal 30 amp breaker, but since you are now plugged into a 50 amp outlet, then it could conceivably burn up if pulling over 30 amps for very long thru it.
However, for that to happen, you would also have to be pulling over 30 amps thru your RV's distribution panel also, and it's main 30 amp breaker should trip. It could go bad or not trip fast enough, but this is doubtful....but could happen.
If you limit yourself to what you usually use in a 30 amp scenario, then you shouldn't really be pulling more than 30 amps thru the cord, even when hooked to a 50 amp capable outlet.
Instead of having two 30 amp circuit breakers (one inside for the RV, and the other outside for the cord and/or RV) to protect it all, you are just going to be relying totally on the one 30 amp main breaker inside your RV's electrical distribution panel. Bad things could happen, but don't know if I have heard of it actually occurring.