RV electrical cords can plug into a campground's electrical grid to power items such as the lights, microwave, refrigerator and even the air conditioner. While plugged in, the cords also recharge the house batteries, which power the various systems when "dry camping," or camping off the grid. The cords are heavy-duty, usually 25 feet long and almost always permanently attached to the RV. The "free end" plugs into the electrical outlet at each campsite.
The amount of amps carried depends on the needs of the RV and the design of the cord's plug-in. Thirty-amp outlets are the most widely used at commercial campgrounds, but some also carry 50-amp plugs for the large bus-sized Class A RVs. Plug adapters are also available to allow the cords to carry 15- or 20-amp service, available at some state parks.
By looking at the electrical cord plug, it's easy to tell the amperage it is designed to carry. Thirty-amp plugs have three metal inserts: one that is U-shaped and at the top, and two rectangular ones on either side of the bottom that are at an angle. Fifty-amp plugs have four metal inserts: the U-shaped one at the top, one long rectangular one underneath it and two shorter rectangular pieces below that.
When booking a campground space, it's important to advise what type of electrical system an RV uses. A 50-amp plug may be used with an adaptor to power a 30-amp rig. When adapting a 30-amp plug to a 50-amp system, it's possible that not all the features on a Class A rig will function.