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How to Fix Burned Wire

Updated: Feb. 10, 2023

How to fix the insulation on burned wire quickly and easily

FH12MAR_CHAWIR_02-2Family Handyman
Fix burned wire inside electrical boxes by replacing charred insulation. You can do this quickly and easily without pulling in new wires.

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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.

Prevent Ice Dams

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 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 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.

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
You’ll also need a lighter

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