Yes, I am using 12g romex. Thank you for the front reply. That's all I needed to know. One of the next few weekends we will get to our lot to remove the AC from the donor and install it in the cargo.
The cargo has the frame reinforced around the vent for AC prep. I am a shop teacher. I have taught construction, electornics, and woodworking. I would use either 12g romex or 10g stranded. I chose romex as that is what is in most campers.
We have ran all wiring for 110 v outlets under trailer in 3/4 pvc with junction boxes. None exposed. All 12v wiring is 14g stranded in sheathing and ran on the inside with grommets wherever it goes through the frame to protect from damage.
All precautions are being taken for electrical. Thanks for the answers
