This is what a 20 amp receptacle looks like.
Don't try and connect to a receptacle that looks like the one below
The contacts inside the 20-amp receptacle are thicker and they grip tighter. I like to see 20 ampere circuits for RV's dedicated meaning they feed nothing else in the house. I also like 10 gauge wire to the receptacle. Follow other respondent's advice about wire size. All 20-amp receptacles are Specification Grade. The one inside your house probably cost the builder 19 cents. He got cheated. They are junk.
