Many times the campground 30 amp receptacles overheat, and then the brass inside the plug loosens, and will not grip the 30 amp plug tightly. This can cause overheating and in extreme cases like yours, arking and possibly a fire (when more extreme!) The fire will not burn hot enough to melt anything other than the electrical cords, and not damage the RV at all, as it should trip the 30 amp circuit breaker.
So if your 50 amp RV cord is still good, then you only need to replace the 50 to 30 amp adapter, as it has overheated to much, and now requires replacement.
I had a 30 amp receptacle overheat on me. I noticed that the voltage was only 105, so I got out my booster transformer (it was about 105F outside!) and found the plug very hot. By plugging in my 30 amp RV to a 50 amp receptacle, I found now I had 120 volts - even with the air conditioner running!
Good luck!
Fred.
