EVSE Garage Pass-through Instructions

Why do this?

I have two plug-in electric cars, with a third one expected next week. For the past few years we’ve been running the cords from the EVSE (What most people call the charger, although technically that’s located in the car itself) out the corners of our garage door. That seemed to be fine for the first 2 years, but I found that my high amperage EVSE, a JuiceBox Pro 40, was no longer working. After a lot of trouble-shooting, I discovered one of the pilot wires had broken from being crimped in the garage door.

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I got fancier with routing the wires from the EVSEs to minimize the cord getting squeezed under the garage door when closed. It works pretty well for the relatively small diameter cord that comes with the portable EVSE included with most GM vehicles. The diameter of my JuiceBox is about 3x this due to being 40A instead of 12A.

I recently saw a post in one of the EV FaceBook groups for which I’m a member showing how someone used a plastic cord hatch, originally intended for an RV or camper power cord, to pass their charge cord through the wall of their garage. Here are my two examples for the two different chargers I currently use…

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This is the end result for the portable charger that came with my Chevy Volt.
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And this is the end result for the larger diameter JuiceBox charge cord.

If you’re sold on the idea, here is a guide to help you replicate the above results.

DISCLAIMER: I provide no guarantees implied or otherwise that the procedure below is safe or will comply with your local building code. You could cause damage to your house by following this guide, or risk injury if you hit live wires in the wall of your garage when cutting holes. Follow this guide at your own risk!

Parts and tools list:

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(left to right) Steel wool pads, 18″ drill bit, Vinyl siding mounting block, 3.5″ hole saw.
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These are the two hatches I purchased. The one on the left was the more expensive of the two listed below.
  1. Vinyl siding mounting block: 6.625 in. x 6.625 in. #021 Sandstone Beige Dutch Lap Surface Universal Mounting Block $13.16 each (technically this isn’t for the siding I have, but I trimmed the edges to match an existing one that was discontinued at Lowes. This one is the correct style but wrong color).
  2. Long drill bit (if you have a finished garage and need to drill though both sides of the wall. 12-18″ is probably sufficient, maybe 1/4″ diameter or so. It’s just to drill a pilot hole. Here’s an example, you can probably find a less expensive one.
  3. 3 1/2″ hole “saw” drill attachment. $25.98
  4. Power Cord Hatch/Cover. $7.95/ea. If you have a finished garage, get two of these, one for the outside of the house, one for the inside. Here’s an alternative, which was the one I saw posted from someone else. This one is twice as expensive and I don’t think is really much better than the less expensive one. I used two of these on the outside of my house and two of the less expensive on the inside, only because I had already ordered and installed one of the more expensive ones and wanted them to match.
  5. Steel wool to “insulate” around the cord inside the hatch. I used 2 packages of these per pair of hatch covers.
  6. Good quality, silicone caulk.
  7. 2″ weather-proof screws (3 per hatch/cover). I used prime guard deck screws that I had on hand. The more expensive hatch cover came with screws, but they weren’t long enough for this application through the vinyl mount, siding, etc.
  8. Power drill for the drill bit and hole saw.
  9. X-acto knife or utility knife to remove the flanges from the back of the hatch cover(s).
  10. Stud finder (if finished garage) to ensure you don’t drill into/through a stud.

Step by step directions:

  1. Prepare the hatches for use. You will need to carefully cut the backs off the hatches as the flanges are two small and firm to allow the entire EVSE charge handle to pass through.
  2. Locate the desired pass-through location on the inside and outside of your garage. Think about where you will be parking your car and ensure the cord will reach. Use a stud finder to ensure the area you are drilling the hole has 2-4″ on either side of the hole free (no studs, conduit, wires, etc.). You can use a tape measure to approximate the height from the ground and the distance from the edge of the door to locate the hole on the inside and outside of the garage.

3) Test fit the mounting block on the siding to ensure it lines up with the location you are targeting. Put the mounting block on top of a scrap piece of wood or other object and using your long drill bit (or equivalent diameter shorter bit if you like) drill a pilot hole in the center of the mounting block:

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4) Now do a second test fitting of the mounting block on the outside of your garage wall. You now have a pilot hole in the mounting block you can use with the long drill bit to identify the inside and outside locations for the hole saw.

You can see I was off by about an inch in my estimated location on the inside wall of the garage using the tape measure estimate method. That’s why we drill the pilot hole, to ensure the two 3.5″ diameter holes we make with the hole saw line up exactly.

5) Now switch to the hole saw attachment in your drill. Place the mounting block upside down on a box or scrap wood of sufficient thickness so you don’t damage the hole saw’s middle drill bit. Using the pilot hole you drilled earlier, drill out the middle of the mounting block. Use minimal downward pressure to prevent the mounting block from spinning. I held it with my foot. A smarter person would use a clamp. 🙂

6) Now you can drill the holes in the outside and inside walls of the garage, where you should have pilot holes from step 4.

(left) Removed siding, plywood visible. (Top, right) With plywood drilled out as well. (bottom, right) View from inside the garage with drywall hole completed.

7) Test fit the hatch and vinyl mounting block in the hole on the outside of the house. Pre-drill small pilot holes where the three mounting holes are on the hatch. Temporarily screw in the hatch through the mounting block to ensure everything lines up well.

8) Now unscrew the hatch and remove it and the mounting block. You are going to use the caulk to ensure everything is water tight.

I put caulk around the hole and between the siding and plywood, around the inside lip of the hatch (not shown) before inserting it through the mounting block, and then around the inside of the mounting block and edges of the tube portion of the hatch where it will come in contact with the plywood. Re-insert into the hole on the outside of the house and put the three screws back in. Be careful not to over tighten the screws. If you slightly deform the front of the hatch by over-tightening the screws, loosen them until everything looks even and flush.

9) Now basically repeat the process for the inside of the garage. You don’t have the mounting block to contend with. While probably not necessary, I put some caulk around the inside lip of the hatch, then screwed it in to the drywall.

10) You may notice a small gap between the two hatches. Use pieces of duct tape to close the gap between the two hatches so it looks like a continuous tube.

You can then push your charge handle through the hatch opening on the inside of the garage and fish it out from the outside of the house! You may need to depress the handle for it to fit through. You can route and secure the cord between the EVSE and the inside hatch door, then close the door. There are two latches that “lock” it closed.

11) Now fill in around the cord inside the tube connecting the two hatches from the outside of the house with steel wool. This should help prevent rodents from making their way through this hole. You would be amazed by how small of an opening a mouse can squeeze through. Try to get steel wool on all sides of the cord so it is more centered in the opening, and fully “protected” by the steel wool.

You can then close the outer hatch. You are done! Unless you need to add a holster to hold the charging handle when it is not in use. I already had these installed from my days of running the charging cables under the garage door. I’ll share more details on those in a separate post.

Please let me know if this worked for you, and if you have suggestions for improvements.

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