Introduction: Construction of a 1inch Electrical Box

About: Technical Editor for two magazines. Software tester for the computer controlled electronic brakes of Locomotives.

It was NOT my intent to create a custom electrical box. However when we were removing the acoustic ceiling tiles from our Living Room, we discovered something that just shouldn't be there, a taped up electrical connection with NO box!

OK we could re-run a new wire except it went across the ceiling and down behind a wall that we had just finished re-siding with "Nickel" wall using 5/16" plywood. That was NOT going to be torn down and the wire run and then rebuilt again!

So, we needed a ceiling box. The nailing strips for the acoustic tile were 3/4" pine and with the thickness of the new ceiling, we needed a box that measured 1" deep. OK, I found 1/2" boxes, 3/4" boxes and 1-1/2" boxes. But NO 1" boxes!

And according to some Internet searches, we were not the only ones looking for a 1" deep ceiling box. The best guess anybody had was to use a 1/2" Pancake box, available from HD or Lowes and a 1/2" ceiling box extension that has to be custom ordered direct from the manufacturer because no one carries them! You can order the extension rings from Garvin Industries here:

They do provide quick service though.

Our wiring would NOT be coming in from above the box, so we had to drill a hole in the side wall for the 3/8" cable clamps using a 7/8" hole saw. We used a Milwaukee 49-56-0704 7/8" Hole Dozer Carbide Hole Saw here:

and if you don't have the arbor with pilot drill bit to mount the hole saw on here:

Oh, and a vice is a must! And it wouldn't hurt to have an electrical circuit tester to verify the wires are "dead"!

Step 1: Install the Extension Ring

Simple operation to install the ring on the 4" pancake box, engage the mounting slots with the pancake boxes mounting screws and tighten securely.Then, using slip lock pliers, squeeze the slot tang towards the outside of the ring, wrapping the tang around the connecting screw.

Step 2: Mount the Extended Pancake Box in a Vice.

You can start like this but you may have to turn the box 90 deg, if the extension ring tries to move when you start to drill.

Step 3: Drill the Pilot Hole.

What should be a simple operation turns into a pain when the two sections try to separate. Not pushing too hard seems to help here as well as a good tight crimp on the connecting screw tang per Step 1.

Step 4: Push the Hole Saw Deeper and Engage the Teeth of the Hole Saw

Here is where the trouble really starts. The two independent sections are only retained by two screws crushing slots and even with then crimp, the two sections want to move independently of each other. Re-tightening of the retaining screws may be necessary as well as a tighter crimp per Step 1.

Step 5: Step 5: Eventually You Will Get a (mostly) Round Hole

Thankfully the hole doesn't have to be pretty. All that is required is that the 3/8" cable clamp fits into the hole!

Step 6: Step 6: Insert the 1/2" Cable Clamp

Push the clamp through the hole and thread the locking nut onto the clamp's threads. Make sure to align the cable clamp's screws as shown.

Step 7: Step 7: Install the Box

The 1960's era black friction tape was removed and the wire nuts were twisted off (with the power off of course!) Two 1-1/4" drywall screws held the pancake box against the plaster ceiling by grabbing the lathe above the plaster. The wires were slid through the clamps at each end and the clamps tightened. The wires were then twisted together and the wire nuts were reused. Now the box sets just 1/4" inch above the old nailing strips and when the new ceiling is installed, it will be nearly flush. A plastic domed cover will be used to cover the exposed box per Code.

So is this safer than simple tape. Most likely. However there was no problem for the past 55 yrs!

So there you go, you can construct a 1" box from off the shelf parts, but I don't want to make too many more!