30-amp service is 120V service limited to a total draw of 30 amps. The power cord from the RV is three pronged. 30-amp service is the most common in the RV industry and used widely in campgrounds throughout the United States.
With 30-amp service, any appliance in the RV can operate by itself. However, due to the 30-amp limitations, you may not be able to run a certain group or all appliances at the same time.
If the RV has 50-amp service, the power cord will have 4 prongs, unlike the 3 of 30-amp service, and is capable of running up to 50 amps of draw. With the 30amp plug, only one prong carries the 120V power. With the 50-amp plug, two of the four prongs carry 120V, allowing the ability to set up power needs according to appliance application. As such, a unit built with two air conditioners, can run both at the same time if they are routed on different prongs, while running other appliances commonly used within an RV.
Despite the power system built into a recreational vehicle, the power system is only as good as the power supply. What this means is that if a campground has only 30-amp service available, a recreational unit with 50-amp capability will only have 30-amp service. A special adapter is required to reduce the 50-amp plug to fit the 30-amp campground receptacles. In other words, with only 30 amps available only one air conditioner at a time may be used. Some campgrounds may only carry 15 or 20 amp power. The best way to know what amperage is available is to call ahead and always carry adapters, which are available at most RV dealers and RV parts stores.
Your unit is also equipped with a "Converter". When the shoreline cord is plugged into a campground (or other appropriate receptacle), this device "Converts" 120 volt electricity into 12 volt electricity. Most 12 volt equipment in your unit will operate from this power source, even if your battery is discharged. The "converter" is also equipped with a "battery charger" which provides a "trickle charge" (slow, low amperage charging) to your battery as long as the shoreline is plugged in to a power source.