How to Fix Christmas Lights Like a Pro This Holiday Season

C.E. Larusso
Written by C.E. Larusso
Updated September 20, 2022
man installing Christmas lights on roof
Photo: amyinlondon / Adobe Stock

Stay holly jolly by repairing your Christmas lights in a few easy steps

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Nothing turns the family Santa into a Grinch faster than a string of holiday lights that won’t turn on, which is why learning how to fix Christmas lights yourself is a worthy holiday endeavor. Whether it’s a few bulbs that refuse to light or an entire strand that stays dark, troubleshooting Christmas lights and doing a DIY fix is a fairly straightforward task. All you need is an hour or two and a few tools—no electrician skills required. Read on to learn how to fix Christmas lights on your own this holiday season.

Why Are My Christmas Lights Broken?

There are several reasons why your Christmas lights have lost their sparkle. Common causes include:

  • One bulb has blown out and created a full outage via a domino effect.

  • The circuit won’t hold power, or a fuse has blown.

  • The wiring is damaged.

  • One or several bulbs are not sitting correctly in their sockets.

  • For battery-operated lights, the batteries could be broken.

How to Prep to Fix Christmas Lights

A quick inspection of your Christmas lights can help you diagnose the problem and move on to a solution.

Visually Inspect the String

Before examining the bulbs, take a moment to perform a careful visual inspection of the strand. Unplug the lights, then check the string for more obvious problems, such as damaged or frayed wiring, or bulbs that are loose in their sockets. If possible, reinsert loose bulbs or, if they won’t give a good firm seal, replace them. If your strand has frayed or damaged wiring, replace the entire string with a new one. 

If the strand passes the inspection, verify that your outlet works. Simply plug in another string of lights or a small appliance that you’ve confirmed is in good working order. If you have a multimeter, you can also use that device to test the outlet.

Identify the Type of Lights

Christmas lights are either incandescent or LED lights. The easiest way to identify which kind you’re working with is to plug in the strand for about 20 minutes, and then carefully touch a lit bulb to see if it’s hot. If so, you have a string of incandescent lights, which work by heating up a filament inside the glass bulb housing. 

 If the lights stay cool to the touch after 20 minutes, then you have LED lights, which produce light by energizing protons that give off light when their energy level changes. In other words, LED lights don’t use heat to create light, so the bulbs don’t heat up. 

 Of course, this method only works if at least one bulb on the string works. If the entire string is out, examine a bulb to see whether you can spot a filament. The presence of a filament generally indicates an incandescent bulb, though not always, as some LED manufacturers insert a “faux” filament to make LED bulbs look retro-chic. 

If you’re still stumped, read the string tag and look for any indication of the maximum number of bulbs you can run together in a series. Incandescent lights can handle up to five strings of 100 bulbs, or ten strings of 50 bulbs, while it’s possible to connect 20 or more strings of Christmas lights.

How to Fix Christmas Lights on Your Own

If replacing a bulb didn’t do the trick, let’s move on to the next steps to get your Christmas lights sparkling again.

Check the Fuse

If the entire strand of lights is dark, a blown fuse might be to blame, and you’ll need to learn how to replace a fuse in Christmas lights. Inside every prong power plug, you’ll typically find the fuses for your light string. 

  1. To check the fuse, slide the compartment marked “open” in the direction indicated by the arrow.

  2. Remove the fuses and hold them up to the light for inspection. The fuse is still viable if you see an intact wire strand between the two metal contacts.

  3. If you need to purchase a new fuse, you can find replacements at most home improvement stores and major retail websites for around $10.

  4. Slide the small cover on the plug’s side to remove the old fuse and insert the replacement.

Find the Bad Bulb on an Incandescent String

If the string of lights is primarily working and only one or two bulbs are dark, it’s easy to pinpoint the bulbs that you should replace. (Hint: It’s the dark ones.) However, if the entire string is out, you’ll need to test each bulb individually to determine which ones you need to replace. 

With incandescent lights, the electricity needs to complete the circuit through every single bulb. That’s why one bad bulb makes the whole string nonfunctional, although longer strings may contain two circuits, in which case only half the string stays dark. 

  1. If you have a light tester, place the light tester next to the first bulb in the string. 

  2. Check the indicator on the tester. 

  3. If the bulb works, the indicator will light up. If not, the indicator will stay dark.

  4. If you don’t have a light tester, find a working socket on the strand of lights and mark it with a small piece of colored tape.

  5. Remove every bulb from the non-functioning area of the strand.

  6. Place the untested bulbs in a bowl, with the tested, functioning bulbs placed in a separate bowl.

  7. Test each of the untested bulbs using the marked socket. If they light up, they can go into the bowl or tested, functioning bulbs. If not, they need to be replaced.

If you’re using a non-contact voltage detector instead of a Christmas light tester, you’ll need to put the device near the section of wire between the bulbs. When you get to a dead section with no voltage, the dead bulb will be located immediately before that wire section without voltage. Replace the dead bulb with a new one. 

Find the Bad Bulb on an LED String

You can check LED Christmas lights with removable bulbs using the same process as incandescent lights. 

  1. Begin at one end of the string and use your voltage detector or LED Christmas light tester to check each section of wire or bulb, respectively.  

  2. For a string of LED lights that’s completely dark, you can also use a more analog method to locate the bad bulb. Take a functional replacement bulb and, one by one, replace each bulb in your string with it. 

  3. When the string lights up, you’ve pinpointed the bad bulb. You’ve also solved the problem, so you can move on to the next step of stringing up your holiday lights.

  4. If you don’t have a light tester, follow the same instructions for incandescent lights.

Hang Your Lights

Hanging lights on a wooden pergola
Photo: Hero Images / Adobe Stock

Now that your lights are all in dazzling and working order, it’s time to hang your Christmas lights around and outside the house. 

  1. Plan your project well. Hang your lights within reach of electrical outlets and only do this project in good weather.

  2. Measure your home’s exterior to make sure you have enough lights. If you plan to hang the lights in bushes and trees, be sure you have enough string to cover the area.

  3. Practice ladder safety and work with a buddy. It’s always a good idea to have an extra set of hands for projects that involve electrical outlets and working at heights.

  4. Attach your lights with staples, light clips, or adhesive hooks. Consider using an extension pole to attach lights in hard-to-reach places.

How to Prevent Damage to Your Christmas Lights

These simple steps go a long way to extend the life of your lights.

Check Your Extension Cords

Your extension cords should be appropriate for your Christmas lights, or you risk a blown fuse. Check to be sure that your extension cords are appropriate for outdoor use, if you’re using your lights outside, and that the amperage of the cords match your lights. In addition, make sure to inspect your extension cords before plugging them into your lights and your outlet to check for any damage.

Use Roof Clips

Using roof clips instead of nails or screws will prevent damage to your Christmas lights wires, as nails and screws can puncture them. In addition, nails and screws can damage your shingles over time.

Set a Timer

Buying a timer for your lights will help you save electricity costs and can prevent burnt-out bulbs, or worse, those that overheat and cause a fire.

Store Your Lights Properly for Next Year

After the holidays are over, take a few extra minutes to store your light strings properly to avoid repeating the bulb-checking process next year. Wrap the strand of lights carefully around an empty cardboard cylinder from a roll of paper towels. Store each strand in a container cushioned by newspaper or tissue paper for extra protection. These protective measures will help minimize the risk of damaged bulbs and frayed wires.

Frequently Asked Questions

Most hardware stores, as well as mega stores like Amazon and Walmart, carry light testers. You can expect to pay between $20 and $30 for one.

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