120v AC black is primary hot/line; red is secondary hot/line. Given 120v AC, shore power or otherwise, in a 2-wire + ground scheme, black is the color for hot, white is the color for common/neutral and green or green with yellow stripe for ground.
Red is used, as an example and again for 120v...
Let's start with: What inverter are you using? I have a Xantrex Freedom XC Pro inverter installed in our little custom Escape fiberglass trailer and it functions as a built in transfer switch that makes going between 120v AC "shore power" to onboard 12v DC seamless and visa-versa that has...