The Problem: Scorched, charred or burned wire in an electrical box
So you’re finally getting around to replacing the ceiling light fixture when you discover that the wiring insulation has turned to charcoal and cracked off. The usual reason insulation gets ruined is that the bulbs in the fixture exceeded the fixture’s wattage rating. That extra heat literally baked the insulation. Usually the insulation outside of the ceiling box is OK. But you’ll have to repair the damaged insulation inside the box. No, you can’t just wrap the bare wires with electrical tape. That’s not an acceptable long-term fix. Here’s the right way to fix the problem.
How to fix burned wires
Photo 1: Get new wire insulation
Peel off the outer jacket of 12-2 nonmetallic cable. Then strip off about 8 in. of insulation from the black and white wires.Photo: Courtesy of The Family Handyman
Photo 2: Reinsulate the old wires
Remove as much old insulation as possible. Then straighten out the old bare wire. Slide on new insulation (white goes on the neutral, black on the "hot"). Hold the insulation in place and slide on a short piece of heat shrinkable tubing.Photo: Courtesy of The Family Handyman
Photo 3: Shrink the tubing
Wave the flame from a lighter under the heat shrinkable tubing. Keep the flame moving so the heat does all the work and the tubing doesn’t burn.Photo: Courtesy of The Family Handyman
Since the wiring in a ceiling fixture is usually 14-gauge, you can fix it with insulation stripped from a 12-gauge wire. Pick up a short length of 12-2 nonmetallic cable and a package of heat shrinkable tubing. Strip insulation off the 12-gauge wires (Photo 1). Next, slide the new insulation onto the old wires (Photo 2). Then secure the new insulation with heat shrinkable tubing (Photo 3). When you’re done, you can connect the new fixture without worrying about the old wires shorting out. Just be sure to follow the wattage maximum of the fixture when you select bulbs.
Required Tools for this Project
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
- Wire stripper/cutter
Required Materials for this Project
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.
- 12 gauge electrical wire
- Heat shrinkable tubing