Plug It In, Outside

by Bill Gehr | Mar 15, 2024 | Pro Tip, RVEXPERT

close up of a hand placing a plug in an outlet on the exterior of an RV

Photos by the author

AC outlets are typically provided inside the front storage compartment, which complicates the process needed to route power cords to appliances and other electrical accessories on the patio. Installing an outdoor outlet in a convenient location is a welcome addition.

Having access to 120-volt AC power outside any RV on the patio side seems like a must for most owners; I certainly can’t live without such an outlet. Surprisingly, the outlet for the outside is typically located on a wall inside the front storage compartment, which is less than convenient. The outlet inside my compartment is against the side wall to the left of the door, and it is usually covered with stored items. I have this area loaded with stuff that I don’t want to put in the middle of the compartment, so every time I need to plug something in, I’m forced to move this equipment around and even out of the compartment.

a pass-through compartment in an RV packed with different items giving no access to the 120-volt AC outlet

Access to the 120-volt AC outlet from the patio was through the front pass-through compartment in the fifth wheel. Unfortunately, it was always covered with stored items that needed to be moved to plug in an appliance or accessory.

Even if this area is clear, the power cord still must be routed through the opening in the floor in order to close the compartment door fully. Bottom line: It was a pain — which led to the installation of a weatherproof outlet on the exterior of the fifth wheel, where it should be. This project is relatively easy and required only a few tools and a couple hours’ time.

I decided to use an exterior extension cord that could be cut and routed from the new outlet and plugged into the receptacle inside the compartment. I found a suitable outlet on Amazon that could be mounted in the lower exterior wall skirt for only $15.42. Just search for “US Standard Power Socket 15A 125VAC Weatherproof Outlet with Cover Outdoor RV.” While I was at it, I purchased 20, 3/8-inch cable clamps with a rubber cushion that were perfect for securing the extension cord, which I already had; the clamps were $9.99 on Amazon.

I also picked up a junction box at the local building supply. Since there was enough room behind the exterior wall, the deep junction box fit easily and gave me plenty of room to install the wires to the back of the outlet without having to fight it. The extension cord was routed through the hatch in the compartment floor to the factory receptacle in the wall and secured in logical locations with the cable clamps. A 14-gauge extension cord was needed to match the 15-amp requirement of the new outlet with ground fault circuit interrupter (GFCI) protection.

Once the permanent location for the new outlet was established, the opening for the spring-loaded door was used as a template for marking the mounting location. Holes were drilled in the corners and the opening in the metal skirt was cut with a good pair of tin snips. After a little trimming, the outlet was test-fitted and the cable routed toward the frame, leaving enough slack to make it easy to pass through the junction box and connect the wires to the outlet. It was necessary to drill a hole in the junction box as it was designed for Romex wire, which is more difficult to deal with than the extension cord cable. After adding ring terminals to the three wires in the extension cord cable and tightening the screws in the outlet, the back was wrapped with black electrical tape to protect against possible shorts due to typical jostling of the fifth wheel on the road. The outlet cover was fitted with a nice gasket so there was no need to seal around it with silicone rubber, but I did seal the hole around the extension cord into the J box and a couple of little holes that were there for other purposes.

the cover plate of the new weatherproof outlet is used to create a template area to cut on the lower metal skirt of an RV

Once the location for the new weatherproof outlet was determined, the area to cut out in the lower metal skirt was marked using the cover plate as a template.

the new outlet being held up against the marked area for the cutout

The new outlet was held up against the marked area for the cutout to make sure it would fit; additional trimming was required because of the tabs.

tinsnips are placed through drilled insertion holes to make short work of cutting the new outlet opening

Holes were drilled in the corners large enough to insert the jaws of quality tin snips, which made short work of cutting the opening.

a uni-bit is used to drill an extension cord cable hole into the junction box

for waterproofing, advanced silicone is applied to the extra, holes on the junction box

The appropriate size hole was drilled with a uni-bit to provide an opening for the extension cord cable into the junction box. The junction box was designed for Romex wire, which made it necessary to seal the extra holes for waterproofing.

a hand hold the junction box with the extension cord cable routed

The extension cord cable was inserted into the junction box before the outlet was wired up. Enough slack was left to connect the wiring to the new outlet without fumbling.

close view of a plier wrench being used to adjust an extension cord wire

New terminals were crimped on the three wires in the extension cord cable. Slots were cut in the ring terminals to make the connection under each screw in the outlet (screws were not removable and stranded wire does not hold without the terminals.)

a drill gun is used to tighten a screw that hold the outlet spring-loaded cover in place on the lower metal skirt of an RV

After wiring the outlet, it was installed through the siding and into the junction box. Next, the spring-loaded cover was installed on to the siding.

under side view of the RV showing the connection between the newly installed junction box and the cable hatch in the compartment floor

The wire was routed from the junction box through the cable hatch in the compartment floor. The hole for the cable was sealed with silicone rubber.

view inside the pass-through compartment of the RV, made empty for installation and showing the cable routed through the hatch and clamped to walls as it leads to the receptacle provided by the manufacturer

close view of a drill gun tightening the screw on a 3/8-inch clamp securing the extension cord just below the manufacturer receptacle

The cable was routed through the hatch, along the walls and to the receptacle provided by the manufacturer. Clamps (3/8-inch) were used to secure the extension cord cable to make sure it doesn’t get snagged by the “stuff” in the storage compartment.

close view of a large L-bracket mounted on the floor in front of the receptacle, a zip tie secures the cord to the mounted L-bracket

Since it was likely a bunch of stored items would end up pushing against the plug and cord, a large L-bracket was mounted on the floor in front of the receptacle to which the cable was zip-tied.

Once completed, the outlet was tested for power and continuity, and it was ready to handle electrical appliances and accessories up to the rated output.

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