How to Fix Christmas Lights

Updated: Apr. 29, 2024

Squeeze another season out of your strings of lights!

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A few minutes




$0 - $20


Burned-out holiday lights, even the cheap kind, are often fixable with a small investment in time and money. Here's how to diagnose and fix common problems.

  As Seen On Saturday Morning Projects  

Tools Required

  • Bulb tester

Materials Required

  • Light string fuses
  • Replacement light bulb

Test, Fix and Change Christmas Lights

Most of us have experienced the frustration of uncooperative holiday lights. After a year of storage, Christmas tree lights often need repairs before they’re ready for use. There’s a simple way to solve the problem. Here, we’ll walk you through how to fix Christmas lights that are not working.

What causes Christmas tree lights to go out?

The most common cause for a strand of malfunctioning holiday lights is a burnt-out, broken or loose bulb. Frayed or broken wires can also cause your lights to fail, so be sure to check that the cords are in good shape. Another reason holiday light strands fail is due to bad fuses, which we show you how to check and change in the steps below.

Project step-by-step (4)

Step 1

How To Fix Christmas Light Fuses

  • Christmas tree light repair is actually really simple.
  • First, slide back the plastic covering on the plug to check the Christmas light fuse.
    • Pro tip: Some Christmas light strings have more than one fuse, in which case they’ll be next to each other.
  • Replace any blown Christmas light fuses.

christmas lights fuse diagramFamily Handyman

Step 2

How to Test and Repair Christmas Light Bulbs

  • Test the Christmas light bulbs with an inexpensive tester.
  • A Christmas tree light tester is an essential Christmas light repair tool. Some Christmas light testers work by sliding each bulb through a hole.
    • Pro tip: Usually, changing a problem bulb (or tightening it) will fix the entire strand.
  • The Christmas light tester will indicate which bulbs are bad and need to be replaced. If you’re wondering how to fix Christmas lights, finding the faulty bulb is often the quickest and simplest fix.
    • Pro tip: For the Christmas light tester to work, the lights must be plugged into the electrical outlet correctly — the narrow “hot” blade into the narrow slot and the wide neutral blade into the wide slot.

christmas tree lights bulb testerFamily Handyman

Step 3

How to Test With a Christmas Light Tester Pen

  • With other Christmas light testers, like the one shown below, you simply touch each bulb. You can test an entire strand in a few minutes.
  • Sometimes you have two or more defective bulbs, so only identifying one bad bulb may not fix the Christmas lights.

christmas tree light bulb testerFamily Handyman

Step 4

Christmas Lights Safety and Storage

  • Keep in mind that inexpensive strings of Christmas lights aren’t durable. So at the end of the holiday season, take down the lights with care.
    • Pro tip: Don’t pull too hard on the wires. A loose bulb, broken socket or frayed wire is sometimes all it takes for the strand to malfunction.
  • After taking down the lights, plug them in before storing them to make sure they still work.
  • Then carefully wrap the lights in their original or similar containers, making sure the bulbs don’t bang together. Proper storage is key to their continued success.
    • Pro tip: Wadding them up in a coil and stuffing them into a box will almost guarantee they won’t work next year.
  • Also, be aware that most holiday light bulbs have short life expectancies, about 1,000 to 1,500 hours. This means the lights are designed to last one to three seasons, depending on your usage.
  • Newer style LED (light-emitting diode) lights are the exception. LED Christmas lights can last 10 times longer than traditional lights.
  • To fix Christmas lights, the only tool you’ll need is a bulb tester.

Christmas Light Safety and StorageAnteromite/Shutterstock