Please move if this is the incorrect place.
I have a portable generator that is mounted to a car trailer. No earth grounds are made from the generator to the ground. There is a service panel inside the trailer with 2, 110v connections and 1, 220v connection. The wires coming out of the trailer are black, white, green and solid bare copper.
I want to make sure to wire this up correctly and is based on US standards. On the L14-30 plug I had the white and black going to the hot poles on the plug and green going to ground. What I did not know is where the solid, bare copper wire went. I had to convert from a NEMA 6-30 plug. When I was disassembling the plug the bare copper appeared that it was just pushed into the end of the plug but not attached to any connections within it.