How to Repair Christmas Tree Lights

Squeeze another season out of your strings of lights!

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

By the DIY experts of The Family Handyman Magazine

Check the trouble spots

Judging by our mail, it seems that most of us have experienced the frustration of uncooperative holiday lights. There’s a simple way to solve the problem. First, slide back the plastic covering on the plug to check the fuse (Photo 1). Some strings have more than one fuse, in which case they’ll be next to each other. Replace any blown fuses. New ones are available where holiday lights are sold and at some electronics stores.

Second, test the bulbs with an inexpensive tester, available where holiday lights are sold and online. Usually, changing a problem bulb (or tightening it) will fix the entire strand. The tester will indicate which bulbs are bad and need to be replaced. (For the 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.)

Some testers work by having you slide each bulb through a hole (Photo 2). With other testers, you simply touch each bulb (Photo 3). 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 problem.

Keep in mind that inexpensive strings of lights aren’t durable. At the end of the holiday season, take down the lights with care. 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. 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. They can last 10 times longer than traditional lights.

The only tool you’ll need is a bulb tester.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • Light string fuses
  • Replacement light bulbs

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