How to Repair Christmas Lights
You're not crazy those lights did work last year. Christmas string lights often burn out the moment you unplug them, meaning you might not notice there's a problem for months. We're here to help! First, we'll explain how to figure out what the problem is, then we'll walk you through how to fix it so you can light up this holiday season!
Troubleshooting Broken Christmas Lights
- Plug in the lights and note how many aren't working.If only a few or half of the bulbs are dark, the issue could be a loose bulb connection, a malfunctioning shunt, or dead bulbs. If the entire string is out, the fuse is probably broken and needs to be replaced.
- Test for loose string light bulb connections by tightening them.Unplug the Christmas lights and then turn each dark bulb clockwise and press gently down on it to ensure it's secure in its socket. If you hear a clicking sound, that means the bulb was loose and that you just pushed it back in place. After tightening all the bulbs, plug the string back and in and see if that repaired the issue.
- Test for dead incandescent light bulbs with a Christmas light repair tool.You can use the Christmas light repair tool to evaluate the individual bulbs in a dark section of string and identify the point where the current is failing.Follow these steps to use it safely:
Place the repair tool between the wires coming out of a light bulb socket that's gone dark and press the trigger.
If the tool hums or lights up, the current to that socket is live. Keep testing sockets until you come to one that doesn't cause the tool to hum or light up. That's the dead bulb you're looking for.
Replace the dead bulb and see if that fixes the problem.
- Test for dead LED bulbs using a non-contact voltage detector.Plug the string of lights into the wall and hold the pen up to each dark bulb in the string. The non-contact voltage detector will beep if it detects a live current. If it doesn't beep, you've found a dead bulb and need to replace it.
- Clear the shunt to find out which bulbs are dead.Christmas lights are connected in a series, meaning a section of it will go dark when one bulb fails. A failsafe called a shunt in each bulb is supposed to prevent this by closing the gap across the burnt-out bulb, but it often doesn't work properly. To identify the dead bulbs quickly, try clearing the shunt with a Christmas light repair tool.
Plug a Christmas repair tool into the wall along with your string lights, then remove one of the dead light bulbs from its socket.
Plug the dead light bulb's socket into the repair tool and click the trigger at least 20 times. This will clean the shunt if it's corroded or dirty, which will allow the current to move past the dead bulb and light up the other bulbs in the string. The ones that don't light up are likely dead bulbs.
- Open the fuse box case and check if the fuses are black.A string of Christmas lights typically has 1-2 tiny fuses in the plastic box attached to the prongs. Unplug the lights and slide the fuse slot covers out with a small, flat screwdriver. Tip the fuses out into the palm of your hand. If one of them is black or the wire inside it is broken, replace both fuses.
How to Replace a Christmas Light Bulb (Incandescent & LED)
- Purchase replacement bulbs that match your light strings.Take the burnt-out bulbs to a hardware store, pharmacy, or home improvement store. Look for new bulbs that match the old ones as close as possible. Ideally, check the packaging your lights came in to see what type of bulb you need.
- Remove each of the blown-out Christmas light bulbs.With one hand, delicately pinch the broken light's plastic socket with your thumb and forefinger. Then, with the other hand, gently pull upward on the bulb to free it from the socket.
If you have a Christmas light repair tool, it may come with a small flat edge that you can use to get underneath the light bulb and pry it out of the socket.
- Insert the replacement bulb into the old bulb's socket.Make sure the two copper wires on the bottom of the bulb fitting are completely aligned with the holes in the socket. Gently press the bulb into the socket until you hear a soft click. Then plug in your lights and watch them glow.
How to Replace a Christmas Light Fuse
- Unplug the lights, open the fuse box, and pry out the blown fuses.Electrician Frank Boss suggests gently levering the blown fuses out with a thin screwdriver or another flat implement like a pen knife.
- Find exact replacement fuses that match the old ones.Most Christmas lights are sold with spare fuses for this purpose. If your spares have escaped from the holiday box, take the blown fuses to an electronics store and ask them to match you with new ones of the same size and voltage rating. 100-light strings typically use 3A fuses, but be cautious and confirm your fuses' rating with a store employee.
Never use a fuse with a higher voltage rating. This can cause a major fire risk in your home.
- Drop the new fuses into the slots in the fuse box.Ensure they're fully inserted, then slide the slot covers back into place and plug the lights into an outlet. If most or all of the lights turn back on, the fuse box is fully repaired.
If the lights still won't come on, try a different outlet in case you blew a house fuse or circuit.
