I don’t know whose bright idea it was to build garages and put only one electrical outlet in them. But it’s common in houses built before the 1970s. I don’t need to put the Taj Mahal out there, but I don’t like snaking extension cords across the garage to plug a tool in. So here’s how to add an outlet to the garage from the adjacent room.
To add an outlet to the garage from the adjacent room, knock out the metal knockout in the electrical box in an existing outlet, then drill through the drywall on the other side. Run a wire from the outlet to the other side. The project only requires a wall-mounted electrical box, a short length of wire, a cover plate, and a GFCI outlet if the circuit isn’t already GFCI-protected.
I had an outlet in my kitchen adjacent to the garage that just happened to come out right next to my toolbox, which has a power strip on it. That’s some good fortune. And since that outlet was already GFCI, I didn’t have to use GFCI in the garage. If you’re jumping off an outlet that isn’t GFCI, be sure to use a GFCI outlet on the garage side.
This project doesn’t take a lot of time or expense. You can do it for well under $25 and it greatly improves the usefulness of your garage.
How to add an outlet to the garage from the adjacent room
First, I found out what breaker it was on, and turned it off. When I took off the wall plate, I wrote the breaker number on the plate. If I did this every time, I’d really save myself some grief. I pulled the outlet out and pushed it out of the way. Mine was in a metal box. I’ve seen people in Youtube videos just reach in with a screwdriver and pop the knockouts right out of metal boxes in walls. Mine didn’t want to play. I had to press a metal rod up against it and hit the rod with a hammer to break off the knockout.
With the knockout out of the way, I drilled a hole into the wall through the knockout. This gave me the locator I needed. From the other side, I drilled a 1-inch hole in the drywall with a spade bit. That’s plenty of clearance for a short length of Romex. To reach through a wall and leave enough slack on both sides, you need about a 10-inch length.
The garage side
I mounted a two-gang metal box on the wall, positioning it so the knockout reached the hole and one of the screw holes could reach a stud. I ran a long screw through the box into the stud, then added a couple more drywall screws in the middle to steady it.
Why use a metal box attached to the wall? This gives me more room to work with, and the metal box makes it easy to run conduit if I ever need to use that box to run a wire to something else. It doesn’t look great, but this is a garage.
With the metal box mounted, it was just a matter of running the wire, hooking it up, and cleaning up afterward. I put cable clamps in the holes to protect the wire. Then I ran the wire through and connected it to the wires on the kitchen outlet. The kitchen outlet happened to be backwired, so the screw terminals were available.
Then I connected the other end to one of my new garage outlets. I also ran short wires from the outlet to a second outlet to fill the box.
That’s all there was to it. The hardest part was figuring out how I was going to remove the knockout. Once I got that done, the project took about 15 minutes.