How to Fix Christmas Lights So You Can Use Them for Many Seasons to Come

Is it bad bulbs, burnt fuses, or something else? Here's everything you need to know to fix your Christmas lights.

Let's set the oh-so-familiar scene of the season: You've pulled all of the Christmas decorations out of storage, set up your tree, and strung it with lights (after detangling them, of course). Finally, you plug in the strand only to realize half of your Christmas lights aren't working.

What now? Before you take all of the lights back off the tree and head to the store for yet another replacement strand, we've got a few tips and tricks for fixing your string lights and getting the holiday season back on track.

christmas tree string lights

Cameron Sadeghpour

Common Christmas Light Issues

Christmas lights aren't the most reliable decoration. While string light technology has improved with time, homeowner-grade lights found at big-box stores aren't always made to last. If your Christmas lights aren't looking their best, here are the three main issues that might need to be addressed:

  • Burnt-Out Bulbs: Because most string lights are designed to carry the electrical current through each bulb, a bad bulb can break the current, causing a portion of the lights to go out.
  • Bad Fuses: In the male end of the strand is a slide-out cover housing two tiny fuses. These fuses can burn out over time, causing the strand to go dark.
  • Worn or Detached Wires: Your Christmas light woes could simply come down to worn or detached wires. Rodents are prone to chewing the insulation of wires, which should be inspected each time they're removed from storage. Additionally, wires can pull from each bulb socket, which will break the electrical current.

Safety Considerations

If your Christmas lights are in bad condition and beyond repair, they should be discarded, as using them can pose a fire and shock hazard. Always inspect the wiring closely before using your Christmas lights. When attempting to repair any Christmas light issue, always ensure the strand is unplugged from any power source.

living room with christmas tree and presents
Jay Wilde

How to Replace Bad Christmas Light Fuses

The quickest way to identify a bad fuse in a Christmas light strand is to plug a separate, working strand into the top of the male plug on the bad strand. If the separate strand lights up, the fuses are good. If not, the fuses are bad. If you don't have a separate strand, check the top of the male plug with a voltage tester.

To replace the fuses, unplug the strand and slide back the small cover located on the male plug. You may need a small flat screwdriver to do so. Use the flat screwdriver to pop the fuses out of the compartment. If it isn't immediately apparent which fuse is bad, replace both fuses with fuses of identical size and amperage. Replace the cover and test the strand.

How to Replace Bad Christmas Light Bulbs

On most Christmas light strands, replacing a bad bulb is quick and easy. Oftentimes, all it takes to identify the bad bulb is to plug the lights in and look for the first bad bulb in the sequence of bad bulbs. It might be as simple as pushing the bulb firmly into the socket, as they sometimes loosen, compromising the connection.

If securing the bulb's connection doesn't fix the issue, a replacement may be in order. Unplug your light strand and remove the faulty bulb. It might easily pop out but sometimes there is a small tab holding the bulb in place. Replace the bulb with a new bulb with an identical size, voltage, and design.

Some string light bulbs are designed with an attached plastic base that simply pops into the socket, while others require you to insert the glass bulb into the plastic base from the bad bulb. In this scenario, straighten the two wires on the bulb and feed them through the two holes in the plastic base. Bend the wires upward in opposite directions and smooth them down before placing the base into the socket.


On many Christmas light strands, each socket features something called a shunt. The shunt's job is to maintain the electrical current when a bulb burns out. However, shunts can malfunction, leading entire sections to be dark even after replacing the bad bulb. To repair the shunt, a shunt repair tool is necessary.

wrapping garland string lights
Jay Wilde

How to Fix Christmas Light Wiring Issues

The thin wires on homeowner-grade Christmas lights go through a lot of wear. After being wrapped around objects and stretched across rooflines, it's a Christmas miracle they hold up at all. Additionally, improper storage can lead to cracked and frayed wires from rodents or other causes. For this reason, you should always inspect your lights before stringing them up.

While some choose to tape over cracked and worn-out insulation, it's safer to discard the string lights. However, if wiring has been pulled from the socket, there is a safe repair option that's quick and easy.

After ensuring the string lights are unplugged from all power sources, use wire cutters to cut the wire from the other side of the socket, removing the socket and bulb completely from the strand. You should be left with two bare wires. Use wire strippers to expose around 1/2 inch of wire, then wrap the two wires around each other. Place an appropriately sized wire nut over the two wires and tighten it until it holds firmly in place. Wrap the wire nut and wire with electrical tape to hold the wire nut in place and prevent water from entering.

Keeping Christmas Lights in Good Condition

To prevent these time-consuming repairs next holiday season, store your Christmas lights on a reel or other secure organization solution, and place the lights inside a container to prevent rodent access. Once it comes time to replace a strand, look for LED string lights, which last longer and use less energy than traditional incandescent lights.

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