RV electrical systems may seem complex to an RV owner but understanding the basics can help you monitor electrical functions in your RV and diagnose basic problems. Unlike a house, RVs have three separate electrical systems, described in terms of voltage levels:

• A 12-volt DC (direct current) automotive system for a motorhome chassis or tow vehicle.
• A separate 12-volt DC system for a trailer, camper or the "house" portion of a motorhome.
• A 120-volt AC (alternating current) "house" power system commonly described with the outdated term, "110-volt."

Hookups
In an RV park, the RV's heavy-duty power cord is connected to a source of 30- or 50-amp 120-volt AC power, often referred to as shorepower, bringing in AC power for house appliances such as an air conditioner, microwave, TV/DVD and anything plugged into wall outlets. The combination of these electrical systems provides amazing flexibility that enables the RV to be a mobile condo — fully functional.

Precautions for 120-Volt AC Systems
RVs can be self-contained for several days, but park hookups make life easier. There are few concerns about performance of 120-volt AC systems, but it's important to include a few precautionary checkpoints in your routine when hooking up to shorepower.
Tip 1:
Upon arrival at an RV park, insert a circuit tester (available at RV supply stores) into the park's 15-amp electrical outlet; you can also use an adapter and check the 30- or 50-amp receptacle. It will signal any problems with polarity or ground connection. If any warning signals are shown, a situation exists that could result in electrical shock in event of a malfunctioning RV appliance. Check with park management and consider moving to a different site. Next, plug the checker into a wall outlet inside your RV. If it shows a fault, the problem is in your RV — not in the park outlet.
Tip 2: Check voltage in the 120-volt AC system.
It may fluctuate. Use a voltage monitor — available in most camping supply stores — that can be plugged into any wall outlet in the RV. A monitor may be included in the electrical control panel of your RV. The voltage level should be about 120 under light load (air conditioner not running) while operating either on outside power or an AC generator. If it drops to 110, it's time for concern. At 105, it's too low. Turn off your AC and inquire about the problem with park management.
Fortunately, there are few problems with the 120-volt AC systems in RVs, and these simple procedures can help you be aware if a problem occurs. What if there is a problem that you cannot fix? If you experience a mechanical breakdown, the Good Sam Extended Service Plan will handle the expense so that you don't have to. Good Sam Extended Service Plan: Get an INSTANT FREE QUOTE We want to pay your RV repair bills!