Most RV’s and camper trailers utilize the same types of electrical systems as those used for an average small home. But in addition to the 110 volt electrical supply, there may also be lights, fans, a refrigerator, or other electrical devices which use a 12 volt supply, like that of a car or truck.

A 12-volt DC system powers the RV refrigerator to keep food cold while the RV or camper trailer is moving from place to place. The same goes for the lights and fans. It also keeps the on-board batteries fully charged. This system relies on the 110-volt AC electrical power supply for amperage.

It is possible to pull a 12-volt power supply from the RV or camper trailer’s electrical system or 110-volt campsite power supply. Then the 110-volt supply can be stepped down to 12 volts after it is run through a power converter and to a particular appliance.

Rewiring a Classic RV

Most of RV systems will switch from the 110-volt AC to the 12 volt DC supply automatically when there is a power interruption. These two electrical systems are treated independently from each other when diagnosing electrical problems, except for determining power to the converter. This translates to:

  • 110 volt power– > converter– > 12 volt power– > 12 volt breaker box — > refrigerator or lights

As in a home, the 12-volt system has its own set of breakers to control each circuit. The lights, fans, or refrigerator may each be on their own circuits, depending on the amperage required. If the converter is supplying 12 volts to the breaker panel and the breakers test positive for voltage, this leaves the wiring or the particular appliance at fault.

Essential Tools and Resources

  • If you are not familiar with electrical wiring or troubleshooting electrical systems there are some very good books available to help you understand and repair common RV electrical problems. I would recommend RV Electrical Systems: A Basic Guide to Troubleshooting, Repairing and Improvement to any novice and experienced electrician alike. It will be an enormous aid to understanding RV electrical systems.
  • Another must for tracing down electrical problems is a voltage meter. This handy tool will allow you to check the circuits for continuity and for the correct voltage required for each breaker. A simple test light can be used but will not test for broken circuits caused by bad wiring or other electrical problems. Both of these tools are inexpensive to own and will more than pay for themselves over time. The voltage meter can be used for home electrical problems as well as any other electrical related problem. Both are offered on this page for a reasonable price.

Troubleshooting Common 110-Volt Problems

  • The 110 volt outlets used in some RVs and camper trailers are prone to shorts because of the way they are installed. Some are merely clipped onto the wiring by cutting into the wires. These types are notorious for not working correctly. Replace these types of outlets with standard house types to put and end to loose connections. Since some of the walls are so thin, a smaller receptacle box may be required for the outlet to fit flush in the walls.
  • Ground fault interrupter outlets are another common cause of electrical problems. These are located in places where a possibility exists of someone touching them with wet hands. They automatically break the circuit when moisture comes in contact with the outlet to prevent shock to the person touching them. A simple reset button must be pressed for the circuit to once again be completed. On occasion they will need to be replaced or the other outlets on the line will not work either. Pay close attention to the instructions when replacing these GFIs.
  • In older RVs and camper trailers you may still find fuses instead of circuit breakers. Since the advent of many new electrical devices, these older fuse systems may not provide enough amperage to handle a microwave or other high amp appliance without blowing a fuse or kicking a breaker. Simply replacing the fuse or breaker with a higher amp substitute may be all that’s required. Replacement of the entire breaker box may be the only option remaining if this doesn’t solve the problem.
  • The newer RVs and camper trailers may have two RV A/C rooftop units which require more amperage than the older models to operate without kicking the standard 30-amp power supply used by many campgrounds. Fortunately, many campgrounds and RV parks now provide 50-amp service for these types of units. When making reservations or checking in, be sure to ask about the availability of a 50-amp hook-up if you own a unit with multiple A/C units.

Keeping your electrical systems in good and safe working order insures a trouble free camping trip with no sudden power outages to ruin the trip. Most problems can be repaired easily if you understand how the system works. RV electrical manuals along with a few inexpensive tools are well worth the cost of their purchase.

If you are completely confused by electrical wiring there are also some very good basic books to start you off. It isn’t very hard at all to check electrical circuits, switches or outlets with an inexpensive voltmeter. Just remember, when touching any wires be sure the power to that particular circuit is off. If in doubt, turn off the main breaker or unplug the RV or camper trailer from the power supply. Happy camping!

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