Installing Ceiling J-Box

Electrical Basics: Installing An "Old Work" Ceiling J-Box

Electrical Basics: Installing An "Old Work" Ceiling J-Box

In This Article:A special hole is cut in the ceiling drywall, the cable is fished into the remodel box and the junction box is clamped in place in the hole.	Related Articles: Index of Electrical Articles Installing An "Old Work" Switch Box Installing A Light Fixture
Skill Level: 2	Time Taken: About 20 Minutes

By Bruce W. Maki, Editor

In my house a walk-in closet had a 4 foot fluorescent light fixture. It was ugly, so I removed it. That left the cable dangling from the ceiling. Since most fluorescent lights have a metal body, that body forms the junction box needed for the electrical connections. Consequently, when a fluorescent fixture is removed, a junction box must be installed in its place.

After I removed the light I patched the holes from the toggle bolts that held the light to the ceiling.The starting point for this project was a cable that dangled from the ceiling. Of course the ends of the wires were capped with wire nuts, and the power was shut off. (In this case, the light switch was off. Sometimes the breaker would have to be turned off.)

This saw is a drywall saw and is useful for cutting circular or rectangular holes is wallboard The blue plastic object is an "old work" or "remodel"junction box. It hangs from the ceiling drywall or plaster and is not nailed into any wood framing. This box is only meant to support a few pounds.

Don't even think about using one to support a ceiling fan. Fans require a special vibration-resistant box that must be connected to the ceiling structure.

I held the plastic box against the ceiling, in upside down position, and drew a line around the outside. Note: this is not the line to cut on.  I could see through the existing hole that a ceiling joist lay nearby, so I had to position the junction box away from the joist.

I made a pencil mark parallel to the first circle, about 1/2" inside.This outlines the body of the junction box.

I used a drywall saw to cut the hole, cutting on the smaller circle.

This completes the initial cut.But... the junction box still won't fit, because of the three tabs that clamp it to the wallboard.

I fed the wires through through the cable opening in the back of the old work junction box. This box has molded-in spring tabs that prevent the cable from being pulled from the box. But the cable can still be pulled further into the box.

Next, I pushed the junction box into the hole until the clamp tabs hit the ceiling. Then I made a pencil mark around each tab.

I pulled the box back out and made cuts for each tab. The object of the game is to make the overall hole as small as possible, leaving as much intact wallboard as possible so the clamps have adequate solid material to hold on to.

I pushed the junction box into the hole. The clamp tabs must beretracted against the body or they will prevent the box from fitting in the hole. If this box was being installed in a plaster-and-lath ceiling then the screws would have to be withdrawn a bit so that the clamps can bite the greater thickness.

Once the box is all the way in the hole, the screws for each clamp are tightened. This step is critical. When the screw is first turned, the plastic clamp arm swings away from the body and stops at a plastic tab. This requires that the clamp arm be backed off far enough from the flange that it does not hit against the wallboard. I always turn each screw a bit and then gently pull on the box. If a clamp is not catching it will be noticed then... not when a light fixture falls from the ceiling.

Once the box was securely fastened to the ceiling, I capped the wires with wire nuts and tucked them into the junction box.

This wiring project will be put on hold until the ceiling paint is touched up. This would conclude the "rough-in" portion of a wiring job on a remodeling project. There is often a break in the action after the rough-in is completed, so the painting or other surface finishing can be done.

Tools Used: Drywall Saw Basic Carpentry Tools

Materials Used: PVC Old Work Junction Box