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Understanding RV electricity By Mark J. Polk All but primitive campgrounds provide RVers with an external 120-volt electric source to plug into. Your RV has a heavy-duty power cord that is normally about 25 feet long. Depending upon the type of RV, it will either be a 30-amp or 50-amp system. After plugging into the campground electric outlet, your rig will be supplied with power. You must have a 120-volt AC power source to use the microwave, roof air conditioner, the refrigerator in the electric mode and the 120-volt electrical outlets. Everything else in the RV works off of 12-volt DC power. When you are plugged in at the campground, a portion of the 120-volt AC current is converted to 12-volt DC current for the items in the RV that work off of 12 volts. These items are: the overhead lights, the furnace fan, the fan over the range, the vent fan in the bathroom, the water pump, LP gas leak detector, stereo, and the refrigerator when it’s in the LP gas mode. If you look at the RV’s power distribution panel you will see circuit breakers like in your house for the 120-volt AC side, and automotive style blade fuses for the 12-volt DC side. When you are not plugged into an external power source you can still use the 12-volt DC system if you have a 12-volt deep cycle marine battery on your unit. As long as the battery or batteries are charged you can use everything in the RV except the microwave, roof air conditioner, the refrigerator in the electric mode and the electrical outlets. Motorhomes have a battery for the automotive system and an auxiliary battery for the coach system. The coach battery is charged whenever the motor home is running, the generator is running, or when it’s plugged into an external electrical source. Motor homes also generate an additional source of 120-volt AC power with an onboard power generator. This unique feature offers an RVer the convenience of 120-volt AC power whenever he needs it, making the unit fully self-contained. The fuel supply for the generator comes directly from the motor home fuel tank. The system is designed so that when the fuel tank lowers to one-quarter of its capacity, the generator will stop to prevent draining all of the motorhome's fuel. Some motor homes have an automatic switch over from an external power supply to the generator. Other motor homes require you to plug the motor home power cord into a generator receptacle on the motor home to use the generator. Now, here are a few tips about RV electricity: First, a 30-amp system is the most common on RVs. The 30-amp plug on your RV is a large three-prong device that looks very similar to a 220-volt plug that used at home to power a stove or clothes dryer. Your RV plug, however, IS NOT for 220 volts, so never plug it into a 220-volt outlet. Nearly all commercial campgrounds will provide a 30-amp outlet that your RV power cord will plug directly into. In campgrounds with a regular house type outlet, an adapter (always carry one of these) can be used with your 30-amp plug to make it work with the house type outlet. You most often find these 15- and 20-amp outlets at state parks and other public facilities. These low-power outlets limit which appliances you can operate. It is even possible to damage some appliances if they don't receive the required amperage to operate properly. Let’s say, for example, that you plug into a 15-amp outlet and you are using a small appliance that draws five amps. That leaves you with 10 amps. Now you turn on the roof air conditioner, whereupon the air conditioner compressor engages. But it needs about 13 amps, which is not available. The result: your air condition may be damaged. Even with 30-amp service you must be selective about how much power you use. If you use too much, the RV will let you know by tripping a breaker in the distribution box, hopefully saving any damage. Here's a short formula that may help you: 30 amps X 120 volts = 3600 watts. So 3,600 watts is the total amount of power you can use before you overload the 30 amp system. Most appliances come with literature that details how much power they consume. Think of it like this: with 3600 watts you could use 36 one hundred watt light bulbs. When you turn on the 37th light you will probably trip a breaker. It's always a good idea to take a voltmeter along with you that you can plug right into the outlet at your campsite. Campground electricity varies depending on the demand placed upon it. If everybody is running his or her air conditioner the voltage may drop below an acceptable level, and it would be wise to wait until it is restored to normal before operating your own energy-demanding appliances. Glance at the voltmeter every time you walk by. You could end up saving yourself costly repairs. Mark Polk is the producer and host of the RV Education 101 Home Videos. Learn more about the videos here. Copyright 2004 by Out West Newspaper |
