How to Troubleshoot Pre-lit Christmas Tree Lights

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Things You'll Need

  • Pre-lit tree

  • Replacement fuses

  • Replacement bulbs

Pre-lit Christmas trees may be one of the great inventions of our time. Future generations have been saved the horror of tangled light strands, hours spent wrapping individual branches and cuts and scratches up and down their forearms all because of these artificial wonders. But when the notoriously fickle holiday lights are permanently attached to the tree, a dead strand becomes a real holiday downer.


Step 1

Replace the fuse if your entire tree, or an entire section that is on one plug, is out. Each strand of lights has a small fuse box, usually hidden behind a sliding plastic door on the light plug. Check the fuses for damage and replace any that have blown using the spare fuses that came with the tree or those purchased from a store that sells Christmas lights.

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Step 2

Look for any lights that have fallen out of their sockets. While many pre-lit trees use light strands that will stay lit if a bulb goes out, a missing bulb will still cause an outage. Replace empty sockets with the replacement bulbs that came with the tree or from a package of replacement bulbs purchased at your local holiday decoration store.


Step 3

Test each individual bulb to ensure it is snug in its socket. Assembling and disassembling the tree each year and adding hundreds of ornaments and decorations can easily loosen bulbs, breaking the circuit and outing the strand. Unplug the tree and press each bulb into the socket, careful not to squeeze or press too hard, before testing the tree again.


Step 4

Inspect the wire closely for any sections that may be cut, damaged or frayed, which is a fire hazard in addition to a possible source of the outage. If the electrical wire inside the damaged outer layer isn't damaged, you can use black electrical tape to seal the area. If the inner wire is damaged, replacing the tree is your best bet.


There are products on the market that are intended to fix broken strands and help find which lights have gone out, such as the LightKeeper Pro.

If one strand is out, you can add a new strand to the tree over the old strand.

Test your lights every year before you cover the tree with ornaments.

Assemble and disassemble the tree carefully each year and store it in a dry, safe place where animals can’t get to the light strands.


Unplug the tree when working with the light strands to prevent electrical shock. Only touch the covered parts of the strands if the tree is plugged in or wear electrician’s gloves.


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