A 30-amp electrical system is the most common type found in Class B and Class C motor homes and in medium sized travel trailers. The plug is three pronged, looking somewhat like a plug for a dryer or a stove used for a 220 volt system in a house. The 30-amp outlet is the most common found in campgrounds and RV parks.
Class A motor homes, large travel trailers and fifth wheel trailers have more amenities that require more amps. These mobile mansions often have two air-conditioners, which are a big power draw, two TVs and even washer/dryers. Most RV parks that have spaces large enough for larger rigs offer 50-amp service. The 50-amp plug has four prongs, three of which are rectangular and the fourth that is an elongated half-circle shape.
Adaptors are used to plug your RV into different types of electrical outlets. If you have a 30-amp rig then you plug your electrical cord into the 50-amp adaptor and then into the 50-amp outlet. You still need to run the same amount of electricity in your rig as when plugged into 30-amp service. Class A big rigs can do the reverse, plug their 50-amp cords into a 30-amp adapter and then into 30-amp service. This does mean that not all of your appliances, such as the two air-conditioners, can be used at once since you are drawing less power. If you do happen to turn too many things on at once, a circuit breaker (located inside your rig in the breaker/fuse box) for the affected appliance should trip before damage is done. Another use for adaptors is for plugging the RV into house current. These adaptors have the three prongs found on house appliance plugs. Different models are made to fit 30- or 50-amp systems.
