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DIY RV Roof Cable Pass-Through: A Step-by-Step Hole Drilling Guide

If you need to install a cable pass-through in your RV roof, you might feel intimidated. Drilling any hole through your RV roof isn’t for the faint of heart. However, with the correct tools and guidance, even the most novice RVers can sufficiently create a professional cable pass-through while minimizing the chance of future leaks. 

Join us as we discuss everything you need to know about drilling a hole in your RV roof, installing a cable pass-through, and correctly sealing your roof. By the end, we hope you’ll be an expert. Let’s get started!

Amazing Roof Penetration #DIY #rvlife #motorhome

What Is an RV Cable Pass Through?

An RV cable pass-through is a crucial component. It allows you to route cables or wires through the roof of your RV. Whether you’re setting up solar panels, a satellite dish, or need to run power cables for an entertainment system, a cable pass-through provides a safe and weatherproof option. 

Cable pass-through devices are typically small, junction boxes or circle-shaped grommets that keep the wires safe. They prevent wires from moving around too much or rubbing against any sharp edges.

My preferred way to do any pass-through is to add a conduit or pipe to pull wires through. This way wires can be added or removed in the future. If you pull the wires through directly, it’s harder to make changes in the future.

Looking for the best junction box? My favorite currently is the ICOTEC systems available at Mobile Must Have

rv cable pass through
I always add a conduit to the roof when adding a pass-through.

Pro Tip: Pick up the best RV roof sealants.

Can You Drill Into the Roof of an RV?

It’s completely possible to safely drill holes into the roof of your RV. It may seem like a daunting task. However, it’s standard practice when installing various accessories like solar panels, antennas, or cable connections. Many RV roofs are designed to support this type of modification. However, following guidelines and precautions to prevent leaks and damage is essential. 

How Do You Keep Cable Penetrations From Leaking?

Water leaks are the last thing you want in your RV, and there are several ways to ensure a watertight cable pass-through. You can place quality sealants like the Dicor self-leveling lap sealant around any seams that might be prime leak locations in the future. Correctly installing one of these junction boxes and sealing around its edges with a self-leveling lap sealant and/or EternaBond roof tape is the best way to keep cable penetrations from leaking. 

Its also critical to make sure your junction box does not leak as well. If your box leaks then water can run right down your penetration into the RV.

leaking junction box on rv roof
Here is a factory-installed solar junction box on an RV roof that was leaking through the box. The sealant failed inside the box, and it leaked into the roof.

How Do You Run Wires Through an RV Roof?

Now, let’s dive into the step-by-step process of creating a cable pass-through on your RV roof. 

#1 Gather the Necessary Tools and Materials 

Before you begin, it’s crucial to gather all the tools and materials you’ll need before drilling any holes in your RV roof. Here are some items you are going to need

  • A Long Drill Bit (for pilot hole)
  • A hole saw with extension
  • Measuring tape
  • A cordless drill
  • A cable grommet or junction box with appropriate cable glands
  • Safety goggles
  • Self-leveling lap sealant
  • EternaBond tape
  • Piece of PVC or conduit to install in the roof

#2 Choose the Best Location for the Hole

Selecting the right location for your cable pass-through is a vital first step. Unfortunately, I cannot tell you where this should be because every RV is different. You should consider factors like the type of cables you’ll be running, the proximity to your equipment, and the roof structure of your RV. Ideally, you want to avoid drilling holes into any supporting beams or causing damage to the structural integrity of the RV roof.

Additionally, choose a location that minimizes the risk of water pooling around the RV cable pass-through. The top of a curve or ridge on your roof is usually a good choice, as it encourages water to flow away from the hole.

Because its hard to know for sure if there are wires or frame in the roof always plan to start with a small drill bit and only penetrate the top layer of the roof, look into the hole to verify there are no wires where you are drilling.

#3 Drill the Hole Using a Hole Saw

Once you’ve determined the best location, it’s time to start drilling the hole. First, measure and mark the location where you’ll drill the hole. Like mentioned above start with a small drill bit and go slow. I always use a camera to look into the hole for any wires.

After penetrating the roof with a small bit you will know for sure that you are in the right (or wrong) spot. This is critical before putting a large hole in the roof. Switch to the hole saw and start cutting away layers. After each layer stops, remove the saw and check the hole. Lots of times, there is foam you can remove and check for frame or wires. NEVER just ram the saw through the roof quickly, if you hit something critical, it will be a HUGE repair.

After drilling, remove the circular material, and you’ll have a hole in your roof! Don’t panic, we promise it will be okay!

#4 Waterproof the Area

The next step is perhaps the most crucial: waterproofing your RV cable pass-through. First, clean and dry the area around the junction box or cable grommet to ensure no dirt or debris will interfere with the seal. My preferred way to create a seal is to use eternabond tape over the whole area and into the hole.

Then, use self-leveling lap sealant around the edge of your cable pass-through, ensuring there are no gaps where water could seep in. Let the lap sealant set for the appropriate time. 

For good measure, you can also add a layer of EternaBond tape over the sealant. This will create a lasting seal and keep your mind at ease during rainstorms. 

#5 Install the Cables 

Now that the RV cable pass-through is in place, it’s time to run your cables through the grommet:

  1. Route the cables carefully through the grommet or junction box. Avoid any sharp edges that could damage them.
  1. Protect the cables so they won’t rub against the roof material, which can lead to wear and potential leaks over time.
  1. Securely fasten and organize the cables on the interior and exterior sides of the pass-through. In addition to routing your cables to the correct device, you can use cable ties or clamps to keep them in place inside your RV. The point is to keep them secure and prevent them from moving around too much when you’re driving. 
installing cables
This is the ICOTEK junction box that is my current favorite for RV roof penetrations.

Suggested Reading: Learn how to mount solar panels on an RV roof.

Ultimate RV Solar System Build Details - Turning an electrical Schematic into Reality (PART 2 )

Become an Expert On Your Own RV

Whether it’s for solar panels, satellite dishes, or entertainment systems, you don’t have to rely on pricey professionals for simple tasks. However, always seek guidance if things go awry; and always prioritize safety.

Becoming an expert on your RV saves you money and empowers you to take control of your adventures on the road. With your cables properly routed and secured, you can stay connected and enjoy all the comforts of home while traveling off the beaten path.

Do you have any questions about installing an RV cable pass-through? Drop them in the comments below!

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About Tom Morton

Tom, a Pacific Northwest native, is our technical genius. Born in Washington and raised in Alaska before settling in Michigan. He's the man who keeps our operation running, both figuratively and literally.

With a background in Electrical Engineering, Tom specializes in RV solar systems and lithium batteries. He made history as the first documented individual to use a Tesla battery module as an RV battery. Tom has personally assisted countless RVers with system installations and has educated thousands more through his videos and articles.

Cinematography is another of Tom's passions, showcased in his work on the Go North series. You can see his camera skills on display in The RVers TV show on Discovery Channel and PBS where he also stars as a co-host.

Tom's mechanical expertise extends beyond RVs to boats, planes, and all things mechanical. He's renowned for taking on maintenance and repair projects single-handedly and is often spotted underneath RVs, making him the technical backbone of our endeavors.

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