Originally Posted by ventura38
i have a norcold fridge on my class A RV and would like to to run it on AC while driving to save on propane. would like to know if it is practical to try to do this if so what is the best way to do it not sure how to set up the inverter to go 12v to 120AC and switch to shore power with out damaging the inverter
You don't say what make/model/year/chassis etc. of coach you're operating here. And that info would or could state, what model inverter or, inverter/charger you already or, don't have. And that leads to, what KIND of inverter you may, or may not have. There are MSW and PSW inverters. MSW is, Modified Sign Wave and, PSW is, Pure Sign Wave. About 99.9999% of the coaches that come with an inverter or, inverter/charger from the factory, come with a MSW inverter, since PSW versions are more costly and, for the most part, are not needed.
Modified Sign Wave electricity is a cheaper form of electricity and, it's slightly different than PSW. PSW is what you have in your residence and the rest of the world. There are some appliances in the RV world, such as many fridges both regular RV absorption style and residential style, that do not play well with MSW inverters. I know this for a fact, since I just went though all of it, in changing out my RV fridge for a residential. My newly installed residential fridge did not like my Magnum, 2000 watt MSW inverter and simply would not run.
So, I wanted that fridge to run while we were driving it and, on occasion, boon dock. So, I purchased and installed a 1000 watt, KISAE PSW inverter that has a built in transfer switch. That inverter will automatically sense whether it has or doesn't have 120VAC and if not, it automatically switches to 12VDC supply, in less than 30ms. In other words, that fridge never knows when the power supply to it, has been switched from 120VAC to 12VDC and vice versa.
But, again, we need to know what you're dealing with, to appropriately answer. You're thought of saving propane, while driving, well, as has been stated, you'd save about a cup of propane, for every thousand miles of driving. It's your choice.