At first glance RV power systems seem to be fairly straight forward. That is until you have your own RV and all of a sudden...something is not working. Sure, we have 110 VAC (alternating current), 12 VDC (direct current) and LP gas. They are separate and distinct power systems, but two of these are directly linked together and one, LP gas, will not operate (on certain appliances) without the other, 12 VDC. Of course, it is the 12 VDC and LP gas which allow us to live comfortably away from our trusty 110 VAC and that's the reason for its use in RV's.

110 VAC

We all know what it is and what it does. It is our primary energy source in our homes. It operates the very same in our RV's but its installation is unique. So those who say the power systems are the same in both applications are simply... wrong, terribly wrong.


The difference between RV and residential AC wiring installation is the grounding. In residential applications where reverse polarity is not a concern the AC neutral (white wire) goes to the neutral bus bar in the service entrance panel which in turn goes to ground, either to plumbing or a ground rod. When all is well electrical circuits work normally without a ground but ground is used as a safety precaution if and when something might go awry. Its only prudent to cover oneself for contingencies, and proper grounding does that.


  • stabilizes voltage under normal operations by providing a low resistance path for current flow.

  • limits voltage from outside source such as another electrical supply or lightning. (all of us "oldies" remember those lightning rods)

  • aids in the operation of over current devices such as fuses, circuit boards and relays.

The RV grounding actually takes place at the power receptacle where we plug in. Using shoreline cords, power adaptors and faulty extension cords can result in reversed polarity so the 110 wiring in the RV NEUTRAL is totally isolated from ground. Why? In the case of reverse polarity a short could feed power to neutral and the RV chassis if neutral and ground were connected creating a dangerous possibility. Thus the difference in wiring. (Note: AC ground in RV goes to RV chassis)


  • AC powers the high energy appliances such as air conditioners and microwaves. It will also power the refrigerator and H2O heater (if so equipped) through a 110 V heating element.

  • AC also powers the converter, battery charging system along with low energy appliances such as TV's, stereo's, computers and sometimes an occasional AC ceiling light.


  • The real confusion is RV power system problems comes with the 12 VDC and LP gas systems where they work in unison.

    Stove and Oven

    This is the one stand alone appliance that functions on one energy source - your LP gas. If you have gas in your tank or cyclinder and your regulator is even half heartedly working your stove will light. A gas pressure problem or gas line problem could effect the oven operation but the stove most likely would function near normal.


    Just because your stove appears to operate correctly doesn't mean "all is well" for the entire LP gas system. Gas pressure is much more critical in the furnace and water heater operations.


Most refrigerators manufactured in the last 20 years were either 2 way or 3 way.

  • 2 way- Operated on AC or LP>br>
  • 3way- Operated on AC, LP, or DC

LP Gas

  • Ignition, ignition monitoring, and refrigerator controls all operate with 12 VDC.
    Moral of the story - inadequate 12V power equals no refrigerator operation on LP gas


  • In the past 3 way refrigerators had a separate DC mode using a DC heating element. Consumer confusion on the real purpose of the DC mode often led to depleted batteries so manufacturers have pretty much went back to the 2 way refrigerators.

Water Heater

  • 110VAC operation (if so equipped) through an AC heating element.

    LP Gas ignition and gas valve operate with 12V power
    inadequate power = no water heater operation in gas mode


  • operates on gas and 12V
    12V operation operates motor, gas valves, circuit board, and thermostat
    inadequate voltage or no voltage will result in either no operation or erratic operation


  • Low Voltage Uses water pump , lights, fans, DC radios stereo's

  • High Voltage Uses steps, power jacks, slide out motors

  • Inverter takes us to the other end of the spectrum, inverting battery power to 110 VAC. WOW!!! The boondockers dream come true for those who can't get far enough away from civilization and still wish to enjoy their computers, televisions, microwave ovens, and air conditioners.


This concludes a brief overview of RV power systems and provides the first step in understanding the importance and the relationship between the different systems. This is the foundation for troubleshooting the various appliances so when you experience problems the first step is to refer back to this page. Happy RV'ing!

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