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Twelve-Volt RV Circuits 102: Adding An Outlet

Fellow truck camper and 12-volt sharp shooter, John Wells, returns with a step-by-step article on installing a 12-volt outlet.  Get your multi-meters ready.


We’re not taking to the high seas for this swashbuckling electrical adventure, but we will be putting what we learned in “12-Volt Circuits 101” to practical use.  It’s time to get out of the 12-volt classroom, and enhance the 12-volt system in your truck camper.

For this example, I’ve chosen to add a 12-volt outlet for powering an Endless Breeze fan.  Endless Breeze fans are essentially freestanding Fantastic Vents, nearly identical to what’s installed in most truck camper ceilings.  An Endless Breeze fan is a very efficient solution for directing fresh air to a truck camper dinette or cabover during hot weather.

Cigarette-Lighter 12-Volt Outlet

Endless Breeze fans use a cigarette-lighter type plug, so our choice for this task will be the corresponding outlet.  The cigarette-lighter outlet is the most common and versatile of all 12-volt outlets, and is similar to the 12-volt outlets found in automobiles.  Once completed, we can not only plug in the Endless Breeze fan, but a wide variety of 12-volt items that use the same cigarette-lighter type plug.  Let’s get started.


Above: The amperage recommendation is clearly printed on the label of our Endless Breeze fan.

Choose An Appropriate Power Source

The first step is to choose an appropriate power source for the new 12-volt outlet.  Checking the label of the Endless Breeze fan (see above) reveals that the expected current draw is 5 amps, or less.

For the installation, we will need to locate an existing 12-volt circuit with wiring near the intended installation site.  The circuit needs to handle 5 amps without overloading.  Any circuit that works when we are unplugged from shore power (and not running a generator or inverter) is operating at 12-volts.  These 12-volt circuits are fair game.

SAFETY NOTE: Amp draw on a 12-volt circuit is cumulative.  For example, if you have a 5-amp light and a 5-amp fan on the same 12-volt circuit, the peak amp draw on that circuit is potentially 10-amps.  This is unlikely as most 5-amp appliances and devices do not operate at 5-amps, but it’s very important to be aware of your total amp draw on a given circuit.  In short, be careful not to exceed 5-amps on a 5-amp circuit or you could overload the circuit and blow the fuse.

On our truck camper, the 12-volt circuits near the kitchen window include an LED light over the kitchen sink, a range hood fan, and a range hood light.  We can determine that these circuits are 12-volt (as opposed to 110 volt) as they operate when the camper is disconnected from 110 volt shore power.


Above: Notice the proximity of the LED light and the range hood to our desired location for the new outlet

The LED light circuit over the sink could provide the necessary 12-volt power, but it would be difficult to conceal the wires needed for the new 12-volt outlet.

On the other hand, the range hood circuit also offers the necessary 12-volt power, offers an easy solution for concealing the required wiring, and provides space for mounting the new 12-volt outlet.  Equally important, the location of the range hood is up and out of the way to protect the new outlet from dirt, debris, loose objects, and water in the kitchen area.  Everything considered, the range hood is an obvious choice for installing the new outlet.


Above:  Here are some assembled tools for today’s project. Various connector options are included.

12-Volt Outlet Installation Equipment

Here are the materials needed to begin the project; a hole saw and drill, a crimping and stripping tool, various lug and spade connectors, circuit taps, color-coded 16-gauge wire, a multi-meter, and basic screwdrivers.


Above: Note the circled entry on the distribution panel identifying the range hood and its amperage.

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