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'Tis the season for dusting off those Christmas lights and planning out your home's festive display. Unless this is your first time decorating for the holiday season, you probably know what to expect: After a season exposed to the elements followed by three seasons packed away in the garage or attic, many of the lights are in sub-par condition, meaning they're not working or are working only some of the time. In fact, it's quite common for an entire strand to not light up when you plug it in again. That doesn't mean you need to toss your lights, though—a strand that's not working will generally have one or more broken, missing, or loose light bulbs. Because strands are wired in a series circuit, the rest of the lights will probably go out, says Chris Maderazzo, CEO of Super Electric.
Luckily, getting your lights back in working order (or identifying that they cannot be fixed and will need to be replaced instead) is relatively easy.
How to Fix Electrical-Related Issues
Oftentimes, a problem with a string of lights may not have anything to do with the lights themselves. Mark Dawson, chief operating officer at Mister Sparky, recommends checking the main service panel to make sure there isn't an issue with the circuit, as it may have tripped. This might sound obvious, but you'd be surprised by how many times this resolves the issue, he says.
Most mini lights have a small cartridge fuse found in the cord plug. Dawson recommends opening this little door, pulling out the small glass fuse and examining it closely for any breakage. "If you do see that the fuse is broken, replace it with a duplicate of exactly the same size and rating, which you can find at an electronics or hardware store," he says. "If the cause is one faulty bulb, you can just buy a replacement bulb to salvage the whole wire."
If the strand of lights is broken (meaning wires are cut or the bulbs won't light up even after following the steps above), it's best to just throw it out. "If the strand of lights is bad and unfixable then I would suggest throwing them away and replacing them," says Maderazzo. "I would never suggest cutting any light strands, ever—this can be incredibly dangerous."
How to Fix the Light Bulbs Themselves
Incandescent and LED are the two predominant types of Christmas lights. "The older style from the '70s and '80s takes the classic larger bulbs, which are becoming scarce and really hard to acquire," explains Lee Fabian, an electrician in St. Pete, Florida. "There may be some new technologies heading to market such as Plasma Tape lights, but they aren't readily available today." For safety, reliability and energy efficiency, he recommends LED bulbs.
If a strand of LED light stops working, it's likely due to one bad bulb. "Sometimes, only one section of the light strand will go out, which makes it easy to locate the problem bulb. However, if the entire string of lights is out, you will need to check every bulb," says Dawson. Once you find the faulty bulb, replace it. "If the lights still don't work, it might be an issue with a corroded terminal, which delivers the charge to make it light up," he says. "Finding a bad terminal is the same process as finding a bad bulb—you have to take every bulb out and look into the terminal to check for corrosion, which you can easily clean out with a small brush or Q-Tip." Maderazzo adds that a corroded terminal will have an orange/copper rust or a white/yellow corrosion surrounding it. Just be sure the lights are unplugged before doing this.
If a broken bulb is the issue, it's best to replace it than trying to piece it back together. "You should always replace a cracked bulb," says Maderazzo. "I would not suggest using glue in an attempt to repair a broken bulb."
If you're trying to fix icicle lights, check that the outlet you're using is supplying power. "You can do this by removing the extension cord and plugging in something else that will verify that it is receiving electricity," says Dawson. "Next, find the icicle strand farthest from the outlet and unplug it to see if the rest of the strands light up." If the lights do ignite, he recommends removing the faulty strand to allow the others to function. "Move down the line of strands and keep repeating this process, as well as checking each bulb to find the issue," he adds.