For our final stop on the Renovation Road Trip, we made the long trek from Racine, WI to Portland, OR, where we met Heather from Just a girl with a hammer.
Yes, it was our final stop, but the very first time on our journey that we were tripped up by a project. Heather had a couple electrical questions, one of which involved a ceiling-box-shaped patch in her living room ceiling. She was hoping it could be used for a light.
Uncovering the box was simple enough. First I scored a line around the perimeter of the patch. Then I used the claw end of a hammer to gently break away the drywall.
Once the wires were exposed, I used a non-contact voltage tester, and it turned out the box was indeed being used—as a buried junction box feeding outlets in two rooms. This is illegal, not to mention unsafe, so we were at least glad there hadn’t been any accidents.
Unfortunately, in the limited amount of time we had, we couldn’t determine the source of one wire in particular (apparently an abandoned switch leg).
Rather than have us spend our visit following every wire through the house, Heather asked that we cut a box in her wall for an eventual light switch. She’d been disappointed in the past by contractors whose work had later required patching, but as she knew from our blog, we’ve done this several times in old plaster walls and gotten good results.
The first step is finding where you want to locate the switch or outlet box. Use a stud finder, finish nail, or knuckle and good ear to find nearby studs.
You want to make sure that you position retrofit boxes 1″ or more away from any studs. If you have drywall, then a keyhole saw is all you need to cut the hole. Exercise caution and keep the saw shallow as you cut. You wouldn’t want to cut the wrong thing inside the wall (electrical wire, for example).
If you have lath and plaster walls (like Heather), the process is more delicate. Trace around the perimeter of the electrical box to be used and then, with a cold chisel and hammer, gently break away the plaster within the traced area. Accomplishing this requires some precision—normally I work along pencil line with the chisel before making an “X” inside that allows the plaster to pop out.
The lath (wooden slats behind the plaster) will be exposed now. Use an oscillating tool or jigsaw to remove the lath by cutting along the outline formed by the missing plaster. If done correctly, the hole will be large enough to hold the retrofit box but small enough for the wings keeping the box in place to do their job. In other words, the hole will be the appropriate size.
Next, go into the attic and find the top plate (usually a 2×4) of the wall in which you want to place the switch or outlet. Drill an 1/8″ pilot hole through the top plate. You should feel resistance for the first 1 1/2″ to 3″, depending upon whether or not the top plate is doubled up or not. It’s a good idea to use a pilot hole and have someone downstairs looking for the bit. If something happens and the bit goes off course, an 1/8″ pilot hole is much easier to patch than the larger hole made by an auger bit.
Follow the pilot hole with an 18″-long, 1/2″ or 3/4″-diameter auger bit. Keep it as straight as possible to avoid damaging the wall or ceiling. With that done you’ll able to feed the wire or fishing line through the wall and into the box.
While we were disappointed there was no time for us to complete the project, Heather was pleased we were able to lead her future electrician in the right direction. On top of that, we left a nice little spot for the light switch—and it won’t need to be patched at all.
Read every dispatch from the Renovation Road Trip right here.
For more on electrical wiring, consider: