How to repair faulty Christmas lights – and why yours might be broken

From locating the fault to fixing broken bulbs, here's how to get your lights back in action at Christmas

A real christmas tree lit up with fairy lights in a living room with a fireplace, decorated with a fir garland
(Image credit: Layered Lounge)

There is nothing more disappointing than plugging in your Christmas lights when decorating for the season and seeing half of them aren't working. 

It wouldn't be the holidays without the perfect Christmas lights casting a cozy glow around your home, so knowing how to fix them quickly without having to replace every set is essential.

Here, experts explain how to fix broken Christmas lights quickly and why they may be faulty in the first place.

How to repair faulty Christmas lights

There are a few reasons why your Christmas lights may be faulty, and working out the cause is paramount to fixing them, begins Joel Worthington, president and electrician at Mr. Electric, a neighborly Company:

‘Indoor and outdoor Christmas lights can falter due to issues like worn-out bulbs, damaged wiring from stress caused by storage and installation and weather exposure, or overloading of the electrical circuits,’ he explains. ‘These factors all contribute to deterioration over time, making breakages inevitable.’ 

Before setting up your Christmas decor, plug in your lights and check each bulb so you don't waste time hanging Christmas lights around your home just to take them down again to repair or replace them.  

christmas trees

(Image credit: Future)

When you do discover a fault, your first job will be to check all of the bulbs. Start by unplugging the cord and replacing the broken bulbs with new ones of the same wattage and voltage, electrician Joel Worthington says. This will, in most instances, fix your problem, signifying that a blown bulb was the cause of your issue. 

If you are struggling to find the offending bulb, Jennifer Felix, homemaker, and blogger at The Classy Home, suggests using a light tester, such as this one from Amazon, to help locate the damaged bulb: 

‘These tools are intended to assist you in swiftly identifying the problem with your indoor Christmas lights without the need to test each bulb apart,’ she explains. You can then quickly swap them out and resume your decorating.  

Lightkeeper Pro Light Set Repair Tool | View at Amazon

Lightkeeper Pro Light Set Repair Tool | View at Amazon
The LightKeeper Pro fixes most incandescent light sets in seconds with the squeeze of a trigger. Simply attach the device to your broken light socket and click the trigger until the lights come on. This package includes a bulb tester, fuse tester, bulb puller, and 10 clear replacement bulbs

tree decorated with pink decorations and bows

(Image credit: Ronny Colbie)

If neither of these tricks rectifies the issue, then you are likely looking at a fault with the wiring itself, Joel Worthington, electrician, says. Unfortunately, this usually means having to replace the whole set of lights to avoid disappointing Christmas displays and fire hazards.


How do you find a bad bulb on Christmas lights without a tester?

If you do not have a light tester, the best way to locate the fault bulb in a string of lights is to use a bulb you know does work and test each socket until the lights turn on. This is a time-consuming process but is the only way to diagnose the issue.

Can LED Christmas lights be repaired?

LED Christmas lights are a little more difficult to repair than older iridescent lights as you often cannot swap out the bulbs. More often than not, a fault with this type of bulb is caused by a faulty wire, more than a broken bulb. It may be that a wire has been broken or frayed when in storage, or there is an issue with the fuse or plug. These issues can be fixed if you have some understanding of electricals, but it may not be as simple a task for those of us less in the know.

One of the best ways to keep your Christmas lights in perfect working order is to securely organize Christmas decorations for storage with dedicated light storage boxes,’ says Millie Hurst, Solved section editor at Homes & Gardens. ‘Wind the lights carefully around a tube to avoid bending the wires too severely and place them in a hard case or bag to prevent them from being crushed between uses. Always avoid pulling on the wire when installing lights, too,’ she adds. 

Chiana Dickson
Content Editor

Chiana has been at Homes & Gardens for two years, having started her journey in interior journalism as part of the graduate program. She spends most of her time producing content for the Solved section of the website, helping readers get the most out of their homes through clever decluttering, cleaning, and tidying tips – many of which she tests and reviews herself in her home in Lancaster to ensure they will consistently deliver for her readers and dabbles in the latest design trends. She also has a first-class degree in Literature from Lancaster University.