The holidays are a magical time of year for many different celebrations. While specific décor may vary depending on the holiday being honored or even specific Christmas traditions, pretty lights seem to always be part of the final look.
When we talk about holiday lights, we typically are referring to string lights with multiple small light bulbs. Just one bad bulb can either change the whole appearance of the decorations or even prevent the rest of the lights from coming on.
Check Your List—Twice!
Before checking individual bulbs when a string of lights won’t operate as expected, there are a few other things to review:
- Verify that the outlet you are using is working. Either plug something else into that outlet or plug the lights into a different outlet.
- Make sure you unplug the lights, then feel the strings for any exposed wires—it might be time to toss this strand!
- Check the cartridge fuse inside of the string lights.
- Are your lights single circuit? If so, the whole string won’t work due to one bad bulb. Multiple strands might mean only half of the string goes out.
After you have ruled out a non-working outlet, bad wiring, and the cartridge fuse, you’ll need to test the bulbs.
Incandescent Lights
If you have the time, simply feel along the strand and make sure each light bulb is screwed in tightly.
Or, one of the easiest ways to test your old-fashioned Christmas lights for the bad bulb is buying using a Christmas light tester, which can be found at Home Depot, on Amazon, or other places, usually for well under $30 total.
You just hold the tester up to each bulb, see if its light comes on to indicate a working bulb, then move on. When it doesn’t light up, it means the bulb is bad and should be replaced.
Use caution when removing a broken bulb from your string lights. Always unplug the lights first before attempting to remove the broken bulb! Follow these steps:
- Unclip the light bulb from the socket on the string. If you have another string, you can use one for a replacement or purchase some replacement bulbs.
- If the socket is broken or missing, you’ll need to replace that too. On your spare string, use a pin to separate the socket housing from the wires.
- Put the new socket on the string where there was an issue. It can help to watch a video with close-up shots of each part, like this one.
- If it was just the bulb, clip it back into the spot where you had the missing or broken bulb.
LED Lights
Did you know that there are now LED Christmas lights? Yes, these energy-efficient bulbs are recommended for all types of use in the home. See this Better Homes & Garden article with more details about the best bulbs to choose.
You can find LED holiday lights anywhere you buy holiday decorations and they come in a variety of colors and styles and sizes. When it comes to replacing a bad or broken bulb, follow the same instructions as above.
How We Can Help with Your Holiday Lights
Installing Christmas and other holiday lights can be a big chore—and even dangerous if you are climbing up on a roof. If you’re concerned about overloading your breaker or causing a power surge, how to safely plug in several strings of lights along with some other festive illuminated decorations, the professionals at Mister Sparky can help.
You may discover that the issue was not a bad bulb, but bad wiring. This will require an experienced professional to troubleshoot the electrical issue and fix it. They can also install additional outlets to ensure a safe holiday for you and your family!
Click here to schedule a visit with a technician today.
FAQs
You can tell which bulb is out on your string of traditional Christmas lights by looking for the bulb that is "burned out" by looking at the tiny little filaments in the light bulbs to see which bulb is "burned out" or has lost it's filament. Many times the bulb will be "smoked" as well.
How to figure out which bulb is bad on Christmas lights? ›
Incandescent Lights
You just hold the tester up to each bulb, see if its light comes on to indicate a working bulb, then move on. When it doesn't light up, it means the bulb is bad and should be replaced. Use caution when removing a broken bulb from your string lights.
How do I know which bulb is out on my prelit tree? ›
Plug in the tree, and begin testing at the bulb closest to the plug. If you're using the LightKeeper, hold down a button on the top of the tool and touch its tip to the bulb. If you hear a continuous beep, it means power is getting to that point on the light string.
How to find the bad bulb on Christmas tree without a tester? ›
Pull out one bulb at a time, and stick a piece of folded up foil into the bulb socket. If the lights come on, you know that's the bad bulb. If they don't, put the bulb back in and move on to the next one. If you don't have any replacement bulbs, you can leave the foil in until you do.
How do you know which light bulb is bad? ›
How do you know when a light bulb is bad? If the light bulb is physically broken or will not turn on, consider it broken. Or, test the bulb with your multimeter and check the reading. The multimeter tests the continuity of your circuit, which is necessary for a bulb to function.
Is there a bulb tester for Christmas lights? ›
You can find two types of Christmas light testers, and knowing which one you need is important. You need an LED light tester if your Christmas string has LED lights. But if it has incandescent lights, you need the Incandescent light tester. A light tester also finds other issues with a light string.
Why are only half of my Christmas lights working? ›
If half a strand is working and the other half is not, you probably have a loose or broken bulb. Start with the first unlit bulb and work your way down, wiggling them to check for looseness. If it flickers, that's your cue to replace it.
What happens when a bulb goes out on a prelit Christmas tree? ›
Each bulb is lit through a filament, which is contained within the bulb's glass case. "One Light Goes Out, Rest Stay Lit" is a technology that uses an internal shunt within the bulb to continue the flow of electricity throughout a light string, even if a bulb has burned out.
How do I know which replacement Christmas bulbs to buy? ›
Use replacement bulbs of the correct voltage and type. Replacement bulbs are not all the same. They may vary in voltage and bulb type. For example, you cannot replace a 35 light set bulb with a 50 light set bulb because a 35 light set uses a 3.5 volt bulb while a 50 light set uses a 2.5 volt bulb.
Why are some of my Christmas tree lights dim? ›
Suggested Fix: Use a light tester to identify and replace loose or burnt out bulbs. If you don't have a light tester, you can check each bulb on the string for tightness and look for visual clues, like cloudy or dark glass, to identify bulbs that need to be replaced.
The idea being that as lamps on the string go out the voltage and heat in each bulb rises, so the master bulb acts as a fuse to prevent overheating and potential fires. replacement with a regular bulb that has a shunt in it has risks.
How do you find a bad bulb in Christmas lights? ›
Use the light tester to check the first and last bulbs on the string, sometimes these are not picked up during a sweep of the light strings and may be the culprit. Check to see if the string has a fuse in the power plug. If the entire string is out you could possibly have a blown fuse.
How do I identify my bulb? ›
All light bulbs have a code to identify their type of fitting. The letters tend to stand for the name of the fitting and the numbers are the diameter of the fitting in millimetres. For example, an E27 is an Edison Screw bulb with a diameter of 27 millimetres.
What does a bad light bulb look like? ›
Defining What Makes a Bad Quality Light Bulb
They exhibit issues like: Dim, inconsistent illumination. Flickering or buzzing. Poor color rendering.
Why is my whole strand of lights not working? ›
The most common cause for a strand of malfunctioning holiday lights is a burnt-out, broken or loose bulb. Frayed or broken wires can also cause your lights to fail, so be sure to check that the cords are in good shape.
Is it safe to use Christmas lights with a broken bulb? ›
Replace any missing or broken bulbs before you string up your porch or tree because they could lead to electrocution, fires or injuries.
