Pre-Lit Christmas Tree Half the Lights Out? How to Fix It

When half of a pre-lit tree is dark, the cause is usually a blown fuse in the plug, a section that is not plugged into the next one, or a loose, missing or broken bulb. Unplug the tree, check the fuse, push every connection together, then look for a bad bulb in the dark section.

The good news is that it is rarely the whole tree. Most pre-lit trees are wired in sections, so a fault in one place usually affects one part. Work through these steps with the tree unplugged and in good light.

Why is half my pre-lit tree dark?

• Section connections. Most trees come in two or three sections that stack on a center pole. Each section's lights plug into the next with a small connector. If a connector is loose or pulled apart, everything past it goes dark.
• A blown fuse. The plug on the light string holds one or two small fuses. A power surge or an overloaded outlet can blow them.
• A loose, missing or broken bulb. On many incandescent strings, a bad bulb can cut the power to the rest of its section.
• A pinched or damaged wire. A strand caught in a hinge or between branches can break.
• Section and pole alignment. If you turn the pole sections wrongly when stacking, the contacts inside may not meet.
• A bad light string. Some failures cannot be fixed at home.

Where the dark part is tells you something

7 fixes to try

1. Unplug the tree and check the outlet. Plug a lamp into it to confirm there is power. If you use a power strip, plug the tree into the wall instead.
2. Push every connection together. Go section by section. Make sure the plugs between sections are fully seated, and that the pole sections are firmly connected.
3. Check the fuse. On the main plug, slide the small cover open. Take the fuse out, and look for a broken wire or a dark mark. Replace it with a fuse of the same rating, printed on the plug or in the manual. Spare fuses often come with the tree.
4. Look at the bulbs in the dark section. Check for a bulb that is loose, missing, cracked or has a bent base. Push each one in firmly. On sets with replaceable bulbs, swap in a spare.
5. Use a bulb tester if you have one. A small tester finds the bad bulb faster than guessing. Work from the first dark bulb outward.
6. Check for pinched wires. Look at hinges, where branches fold and where the light cord runs along the pole. Gently free anything caught.
7. Try one more outlet. Plug the tree in somewhere else, with no extension cord, to rule out a weak circuit.

What about LED pre-lit trees?

Many newer trees use LED lights. They last longer and run cooler, but the bulbs are often not replaceable. For an LED tree, check the connections and fuses first. If a section stays dark, the issue may be a failed circuit in the string. Contact the maker, because many trees have a warranty, and some brands send replacement sections or lights. Have your model number and proof of purchase ready.

Can you add lights instead?

Yes. If a section is dead and no fix works, many people just wrap an extra string of lights around the dark part. Use lights rated for indoor use, and match the type (LED or incandescent) so the colors look alike. Check the total wattage you are plugging into one outlet, and do not use more than the manufacturer allows for connected strings.

Is it worth repairing or replacing?

A fuse or a bulb costs very little. Time is the main cost. If the tree is old, the plastic is brittle or the wiring is damaged, a new one is safer. Retail sales are often best in the weeks around Thanksgiving, so see when Black Friday is if you decide to buy.

Outlets and breakers

If the tree or its string trips a breaker or a GFCI outlet, the problem is not a bulb. See Christmas lights that trip a GFCI. If you rely on a space heater in the same room, the circuit may be overloaded, as in a space heater that keeps tripping the breaker.

When to call a professional

A tree is usually not a job for an electrician, but stop and replace it, or call the maker, if:

• You see frayed wire, cracked sockets or scorch marks.
• The plug or cord is hot, or you smell burning.
• The breaker trips every time you plug it in.
• The fuse blows again and again after you replace it.
• Large parts of the tree stay dark after you check connections.

What not to do

• Do not use a higher-rated fuse than the one printed.
• Do not run several trees or heavy lights from one extension cord.
• Do not leave the tree lit unattended.
• Do not cut, tape or splice the wires.

Bottom line

Unplug the tree, check the section connections and the fuse, and look for a loose bulb in the dark part. Those steps fix most half-dark trees. If an LED section is dead, contact the maker, or add a string of lights and enjoy the season. If your whole house goes dark in a storm, read what to do if the lights go out.