Wiring a 220v 50 amp RV outlet to home breaker box

[Dane]

By reading posts on this forum I found that breaker box neutral and ground wires are bonded to the same bar, but they are separated in the sub panel. I don't have a sub panel but am wiring a 50 amp RV outlet to the main breaker box. So how do I do this----run three wires (including common) from main box to the outlet and then run ground (green) from to outlet to outlet box? This separates neutral from ground at the outlet but what function does the ground do if it's not eventually grounded to earth? Please----------What am I missing--------Dane

 

[MrModify]

Dane, Are you in the US ?, 120V or 220V