How to Install a 12 Volt Outlet in your Camper
by Dave Michaels
AOC DIY Editor
These days, a lot of camping accessories, such as fans, lamps, computer chargers, cell phone chargers and immersion heaters, require a 12-volt outlet (also called a cigarette lighter, its politically-incorrect name from earlier times). While many campers come with one of these, others don’t. And sometimes, more than one might be nice. So, today let’s discuss how to install a 12-volt outlet into your camper.
First, your camper must have a 12-volt DC source – either a converter (which converts 120 volts AC shore power to 12 volts DC - remember our Aliner Way
discussion last summer about camper circuitry? Of course you do…) or a battery or both. If you have a battery, then your 12-volt outlet will work as long as your battery is charged. If you have a converter and no battery, then your 12-volt outlet will only work when you’re connected to shore power. If you have both, then your 12-volt outlet will work on either shore power or battery power.
Installing a 12-volt outlet is not complex. You should be willing to drill a hole into a surface inside or outside of your camper, and also be willing to install some simple wiring. You probably have most of the tools you’ll need: a drill and a selection of drill bits (including a 1” hole-saw bit which is available from hardware stores), screwdrivers, pliers, and hammer. You also need tools to strip and crimp (or solder) your wires: a combination wire stripper-crimper is inexpensive and useful. Lastly, you’ll need parts - a 12-volt outlet, appropriate sized wire, insulated staples, electrical tape, an in-line fuse holder, a few 10 or 15 amp fuses (depending on the rating of the 12-volt outlet you bought), and crimp connectors. These supplies are widely available at hardware and auto-supply stores.
Start by identifying a location for the outlet, inside or outside the camper. Look carefully behind that surface, to insure that there’s room for the rear of the outlet, including wires. Also be sure there’s an accessible path to route wires from the outlet to your battery or converter. Check everything twice – it’s much easier to check twice and drill once, rather than the reverse.
Drill a 1/8” hole through the mounting surface. Check again to insure there’s plenty of space behind the hole. Then use the hole-saw bit to enlarge the hole. If your 12- volt outlet is a stand-alone automotive unit, then slide it into the hole you made, and screw the metal retaining body onto the rear of the outlet, so it’s tightly fastened to the mounting surface. If your outlet is a marine unit with an integral mounting plate, then slide it into the hole you made, and fasten the mounting plate to your mounting surface with screws.
Next, it’s time to route wires! The size of the wire (its thickness, expressed as an AWG gauge) depends on the amperage rating of the outlet (10 or 15 amps) and the length of the wire from the battery to the outlet. In you’re installing a 10-amp outlet, then use at least AWG 18-gauge wire up to a run of 10’, or 16-gauge wire for runs up to 25’. For a 15-amp outlet, use at least 18-gauge up to 10’, 14-gauge up to 20’, and 12-gauge to 25’. You’ll need to route two wires, one for the hot (12-volt) side of the circuit, for which a black wire is commonly used, and the other for the ground side of the circuit, for which a white wire is commonly used. These two wires should be fastened to wooden support structure along their route, using insulated staples, to keep the wires from moving around when you tow your camper.
At the outlet end, attach crimp type connectors, typically supplied with the outlet, to the two wires. You can either crimp them on using a wire crimping tool (squeeze HARD – you’re making a mechanical connection strong enough to not shake loose!) or you can solder the connectors onto the wires. Either way, you’ll need to strip about ½” of the wire insulation from the end of each wire, exposing the copper strands inside. Then attach the connectors so the wires are firmly in contact with each. Lastly, slide the connectors onto the back of the outlet, observing polarity – the hot (black) wire goes to the center of the outlet, and the ground (white) lead goes to the side of the outlet. Don’t reverse these connections!
On the battery or converter end of the wires, install an in-line fuse holder at the end of the hot (black) wire. Most of these in-line fuse holders have two short pigtail wires attached to them – strip ½” insulation off both wires, then choose either one and splice it to the hot wire leading to your outlet. Wrap the hot wire and the pigtail firmly around each other, then solder the connection and wrap it with electrical tape (or you may use a crimped “butt connector”). If you have a battery, attach crimp eyelets (ring connectors) to the free pigtail and to the ground wire. Install the fuse eyelet under the positive battery wing nut, and the ground eyelet under the negative battery wing nut.
If you have only a converter, with no battery, then look at the wires coming out the back of your converter. The ground wire from your 12-volt outlet goes to the bundle of white wires behind your converter. The pigtail from your hot wire fuse holder goes to a red wire coming from the rear of your converter. Likely this red wire is capped – if so, remove the cap and solder the pigtail to the wire. If there’s no red wire, sometimes a blue, yellow or brown wire coming from the converter can be used. If you find the red wire capped, you can skip the in-line fuse, as the last fuse on the right inside the converter panel will protect your new 12 volt
outlet. The wire colors I’ve just mentioned are based on an Elixir 20 amp converter – unfortunately, your wires may vary.
Push a 10 or 15 amp fuse into the in-line fuse holder, and you have a 12 volt
outlet! Want more outlets? No problem – we have two 12 volt outlets on the outside of our camper, and five inside! As long as they are fused, you’ll have protection against short circuits, and a mighty handy way to connect 12 volts appliances to your camper’s power supply!