How to Replace Dead Christmas Tree Lights

Co-authored by wikiHow Staff

Last Updated: September 15, 2021

Christmas lights are a great way to decorate a tree during the holidays. They easily brighten up your home and can usually last for several seasons. However, the bulbs do burn out over time and must be replaced if possible. There are a few ways to diagnose and fix dead bulbs to continue to enjoy your strand of Christmas tree lights.

Part 1

Part 1 of 3:

Preparing to Fix Bulbs

1
Get replacement bulbs when you buy your lights. Purchase replacement bulbs for your Christmas lights at the same time that you buy your string(s) of lights. They are often sold at the same places and you are more likely to find ones that fit the kind you buy at the time rather than months or years later when you need them.
- Your package of lights may already come included with a few replacement bulbs.
- Make sure any replacement bulbs are of the same voltage as the original strand. Look on the package to determine the correct voltage for bulbs.^{[1]
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- If you cannot find a pack of replacement bulbs for your light strand, simply buy a second short strand of the same lights so you can use the bulbs from it as replacements.
2
Determine the source of damage. Plug in your string of lights to see which of the following problems is occurring in order to adequately solve it:
- There are a few individual bulbs that are not working at random across the strand. This indicates the easiest solution, which is to just replace the individual bulbs.
- There is a whole section of the strand that is not lit. This is common, as light strands are often wired in series, so one bad bulb will affect the following bulbs in the string. You should be able to replace one or a few dead bulbs to fix the rest.^{[2]
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- All of the bulbs in the light strand are not lit. This could indicate a problem with a fuse in the string, or with a few bulbs affecting the entire circuit.
3
Test each strand individually. Disconnect light strands from each other if you have several strands attached in one long string. Test each one in an outlet to determine which strand(s) are the source of the problem.
- One or a few bad bulbs on one strand can affect the other strands, as they operate in a series circuit when connected. Or, there could be problems on more than one strand.
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Part 2

Part 2 of 3:

Checking for Non-Bulb Problems

1
Check your power source. Make sure that your power source is reliable and is not the cause of your light failure. Ensure that the switch is flipped to “on” if you’re using a power strip or surge protector, and that there is power going to the room of your home where you are plugged into an outlet.
- You should try plugging your string of lights into several different sources of power to determine if one of them is the source of the problem.
- If your power source is not the issue, be sure to unplug your lights before proceeding with any further adjustments or fixes to the bulbs.
2
Check the fuse first. Before you check the bulbs themselves, pop open the cover on the end of a string of lights with a small screwdriver. Gently remove the glass fuse(s) and replace if brown or burnt in appearance.^{[3]
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- You can buy replacement fuses for Christmas tree lights at a hardware store or where light strands are sold.
- Plug the strand back in once you’ve replaced a burnt-out fuse to see if this fixed the problem.
3
Check the strand and sockets for damage. Lay out your string of lights and look for any damage or fraying of the wires that connect bulbs. Also look for damage of the plastic sockets where the bulbs fit in.
- Discard a string of lights if you see either wire or socket damage. Replacing the bulbs will not solve the issue in this case, and the strand is considered unsafe for further use.
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Part 3

Part 3 of 3:

Replacing the Bulbs

1
Check first for loose connections. Look at the bulbs on your strand of lights to be sure that each one is seated firmly into its plastic socket, as they sometimes come loose.
- Focus first on looking at individual unlit bulbs, or the first and last bulbs in a section that is unlit, but you should check all bulbs for loose connections.
- Gently push a loose bulb down into the socket until its connecting edge appears flush with the socket or it clicks into place.
2
Replace dead bulbs. Remove any bulb that you know for certain is dead, either because it is an isolated unlit bulb in a strand of otherwise functioning bulbs, or it is clearly shattered, burnt-looking, or otherwise discolored.
- Gently remove a dead bulb by grasping it between two fingers and pulling it up out of the socket. Some bulbs may require you to twist the bulb before pulling up.
- Replace any individual dead bulb with a new one of equal size and wattage, placing it firmly down into the socket.
3
Test bulbs in a dead section. If you have a section of unlit bulbs in the strand, use a bulb tester, found in stores where Christmas lights are sold, to determine which bulb is causing the problem.
- Inexpensive bulb testers can be found as a plastic mold or pen-shaped tool powered by a 9-volt battery.^{[4]
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- Start with the first and last bulbs in an entire strand that is unlit, or the first unlit bulb that follows a section of working bulbs.
- Follow the individual instructions provided with your bulb tester for proper use. Remove any bulb you discover to be dead and replace with one of equal size and wattage.
4
Test the strand after you’ve replaced bulbs. Plug your strand back into a power source after you’ve replaced any bulbs found to be dead to determine if all bulbs are now lit.
- You may need to replace more than one bulb in a section of unlit ones. Continue to test all bulbs in an unlit section if replacing just one doesn’t solve the problem.^{[5]
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5
Continue to care for bulbs when stored. At the end of the season, of after you’ve replaced bulbs, ensure that others are not broken or damaged by storing them where they will not be crushed or exposed to extreme temperatures.
- When putting up or taking down lights, be sure not to pull too hard on the strand, or otherwise roughly handle the wires and bulbs in such a way that could damage them.
- Coil your light strands neatly around a piece of cardboard, a clothes hanger, or other sturdy object, then place them into a box where there will not be pressure placed on the bulbs or wires.
- Note that typical Christmas tree lights usually have a life of about 1,000-1,500 hours, or about one to three seasons of use (unless they are LED lights, in which case they can last much longer).^{[6]
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  Research source} Plan to replace light strands every few years rather than continuing to attempt bulb replacements beyond the strand’s expected lifespan.
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Community Q&A

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Question

How do I remove and install the mini bulbs?

Kearoe

Community Answer

Those little bulbs actually come out of the green connector socket. You just have to pull them a little and they should pop right out. You can replace it with a fresh light by just popping a new one in the socket.

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Question

When I replace a burned-out bulb, the new one doesn't burn brightly. I checked the string to make sure I had the correct wattage and I did. What am I doing wrong?

Kearoe

Community Answer

The replacement bulb may not be as compatible with the string of lights. Make sure you have the same brand and light type.

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Question

My lights were all working, then they all went out at once. What could be the problem?

Community Answer

If one bulb goes out on the string, then they all will go out. The only thing you can do about it is buy a new string of lights, and this time buy the more expensive strings with a different type of circuit, one that won't ALL go out at the same time.

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