Here is a link to Xantrex that gives a short explanation of how their inverters work.
http://www.xantrex.com/web/id/8/learn.asp
If you want to know what your inverter runs, unplug the 110 volt power cord to your coach, make sure the inverter is in the "invert" mode, check to see what works and what don't. Usually it is the TV's, microwave, the 110 plugs at the TV accesory cabinet and a couple of plugins thru out the coach.
The inverter does NOT supply enough power to run the air conditioners or the refrigerator.
I am assumimng the you have a 2000 watt inverter since that is what is usually supplied.
On the Xantrex web page on the right side are some links with for Inverter Selection Worksheet that gives some explanation of wattage requirements for some items that might help you understand voltage to watts for your inverter size.
Ron