There are a couple of things to keep in mind when installing a 12v inverter in an RV. Whether it be a motor home, a 5th wheel, or a popup trailer, the installation concerns are the same.
The first and foremost thing that you should concern yourself with this type of installation is wire gauge. The farther your inverter is from the battery, the heavier the wire should be. With low voltage 12volt power that will be supplied to the inverter from the battery, long wires mean voltage loss. If you have 12.7 volts coming out of a freshly charged battery, you might only have 10 volts that actually reach the inverter if your wires are too thin and there is a long distance from the battery to the car power inverter. Not to mention, using too thin of wires may cause them to get hot and cause a fire.
If you are going to install the power inverter in the front of a 35′ RV and the batteries are in the rear, you’ll need to use really heavy gauge wiring. Most power inverters will have a chart in the instruction manual that tells you what gauge of wire to use depending on the distance. If you have to use 30 feet of wire to supply power to your inverter, you might have to use 6 gauge wire. Wire gauge is backwards from how you think it should be. 12 gauge wires are thinner and 8 gauge. Lower the number, thicker the wire. Be sure and consult your instruction manual for the gauge of wire you should use for your particular installation.
Next you need to make sure that the wires are secure and out of the way. You don’t want to run the wires on the inside from the battery, in front of the couch, down the hallway, taped to the wall in the bedroom and then finally get to the inverter. They’re likely to get stepped on and it will look awful. Either run the wires secured along the frame rail under the RV or trace the wires that are going from the battery to the power converter and fuse panel and run the wires in the same space.
Lastly, be sure and install the inverter someplace where it will be out of the way. You don’t want to install it someplace like on the counter next to the sink. It’s likely to be in the way there and it could possible get wet and destroyed. A better solution might be to fasten it to the bottom of the cupboards with the provided mounting screws. This way it’s out of the way but still easily accessible. A better solution still would be away from water all together. Water and electricity don’t play well together and can create a dangerous situation.
Oh, one last thing. Be sure and screw the inverter down securely. Many people get lazy and skip this step. Inverters come with mounting tabs and hardware for a reason. They last longer if you can minimize the vibration the are exposed to. Screwing them down will limit the amount of vibrations that your inverter will see as it’s traveling down the road in your RV.