The black wire on my plug is burnt up...

Sounds to me like he was running a 50 amp RV from a 30 amp pedestal, not the other way around. A 30 amp RV couldn't pull enough amps from a 50 pedestal to melt anything unless he was running electric heaters. With former RVs I learned my lesson, burn propane not wiring.

you can't put 50 amps thru a 30 amp cord. the 30 amp main breaker will trip long before any damage can occur. Problem as a loose connection.

If you just replace the burnt ends and make no other changes, expect the same results. You can't put 50amps through a 30amp cord without melting something!

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Just replace the burnt parts
A poor connection caused excessive heat.

Jerry Parr

You said you were plugged into a 50amp pedestal and adapted down to a 30amp cord. Common sense tells me the 30amp cord is only capable of safely carrying 30amps. Anytime you approach 30amps, that cord will begin to heat. The heat causes rapid oxidation. The oxidation creates an increased resistance to the flow of current. The increased resistance results in more heat. From that point on it's like a dog chasing its tail. The more heat, the more oxidation, the more oxidation the more resistance and therefore even more and more heat - your plastic plug melts or worse yet catches fire. During all this you've never come close to the 50amp load required to trip the breaker and open the circuit so the process continues until somehow power is interrupted.

You can minimize some of that oxidation by using a di-electric grease" available from Camco at RV supply stores or from Permatex at auto parts stores. I've been using it for years with great results and haven't burned up an plugs - but then I try not to overload them either.

Pulling too much power through corroded connections. This can happen to me when I run the a/c and my water heater is on electric. You have to assess what are your big draws and try not to run them at the same time.