hey man. ran into an issue. was seeing if you could help. So I found out my trailer plug im using only takes 12/3 and 10/3 wire. So I had to go with 12/3 due to budget. My trailer plug holds three wires, one black, one white, and one green. As I was stripping the 12/3 wire I bought, I noticed it had 4 wires. One black, one white, one red, and one without a jacket, just a plain copper wire. The package said it came with "grounding" or something. Im just not sure what to do with the red or the plain wire. Did I buy the wrong thing? Much thanks.