How to Fix Christmas Lights When Half the String is Out

When part of your Christmas lights isn’t working, finding the problem can take out the fun in putting up holiday decor. Most light strings are usually two sets connected; that’s why half of it can blow out, it means the circuit has broken on one side of the series connection.

Start by identifying the problem, then fixing any loose bulbs and replacing blown bulbs. If that doesn’t work, you’ll have to reactivate a faulty shunt with the help of a few simple tools available in your local hardware store. Instead of buying a new light set, here are a few easy steps to identifying and fixing the problem.

Corroded plug prongs

Corrosion on the plug prongs may add resistance and prevent the required voltage from passing through, allowing only part of the light set to function. To fix the issue, rub the prongs to remove the brown substance with medium or fine-grit sandpaper and wipe the dust off with a dry washcloth.

Ensure the metal parts are not in contact with moisture. Proper storage of your Christmas lights will help prevent your plugs from damage.

Loose bulbs

Bulbs can loosen from their sockets during packing and unpacking. To check for loose bulbs, plug in the lights to power and shake the light set gently and you’ll notice flickering on the loose bulbs.

How to fix a loose bulb

• Unplug the light set.
• Pull out the bulb from its socket and check for the two wires protruding at the bulb’s base. These wires should not be touching each other.
• Make sure they lay flat against the bulb on the outside.
• Return the bulb to its socket, and these wires complete the circuit.

Always tie your light sets around a cardboard piece during storage to prevent tangles and loose bulbs. Also, make sure you use the right size when replacing bulbs; the wrong fit may not sit in the socket tightly.

Check more how to tips and tricks on this Christmas Lights: Your Comprehensive Troubleshooting and How to Guide.

Faulty bulbs

One faulty bulb can knock out a whole section of Christmas lights, requiring a replacement with an identical bulb. You can check for a blown bulb by plugging in the light set and checking for any bulb that isn’t lighting. You can also use a voltage tester or light repair tool to test the bulb sockets for electrical current in the dark section. The bulb that doesn’t respond to the tester is the burnt one.

Keep in mind that the dark section can have more than one burnt bulb, so check the whole section for burnt bulbs, mark them, and then replace them.

How to replace a faulty bulb

• Unplug the light set from power.
• Pull out the faulty bulb with its plastic base. Some replacements come with the plastic base attached; if not, use the old one.
• Straighten the wires on the new bulb, thread them through the two holes at the bottom of the plastic base, and then smooth them.
• Slide the new bulb with the plastic base into the bulb socket.

Tip: Consider buying an extra light strand to act as a sacrificial strand; from this, you can get plenty of identical bulbs for replacement.

Blown fuse

Light sets have two fuses in the male plug. A blown plug will prevent the current from reaching part of the light strand. Use a voltage tester to test the wires coming out on both sides of the fuse. A blown-out fuse does not conduct any electricity. Another way to know if a fuse has blown is when the fuse’s glass part looks dark or burnt. Use a fuse replacement with the same amperage and size as the original one.

How to replace the fuse

• Unplug the lights and slide the hatch open in the plug.
• Using a flathead screwdriver, pop out the fuse and replace it with a new fuse and close the hatch. Then test the lights.

Broken filament or faulty shunt

Incandescent bulbs ( they have a filament that glows when heated by electricity passing through it) have a shunt that allows the current to flow through the bulb base. That means the shunt enables the bulbs to light through a faulty bulb.

How to repair a defective shunt.

• Plug the strand to power to identify the burnt bulb and mark it.
• Unplug the strand then remove the burnt bulb, which will be the first in the dark section.
• Insert the light repair tool into the bulb socket and squeeze the trigger about 15-2 times to activate a circuit into the light strand. This tool will send a pulse that will reactivate any faulty shunt on the strand.
• Replace the bulb and plug in your Christmas lights.

Check this too: How to Hang Christmas Lights Outdoors Without Nails

The best way to prevent bulbs from blowing is always to replace any burnt bulb on a functioning light strand. It is because a series connection has a specific maximum voltage that it can take, so when one or two bulbs burn out, the remaining bulbs contend with more voltage than they should, reducing their longevity.

Tip: If the copper wires on your light strands are uncovered due to damage, it’s wise to replace the light set with a new one. Otherwise, you may risk starting a fire or getting electrocuted with exposed wires.

Proper storage and handling of your Christmas lights are all it takes for durability. Christmas lights are pretty inexpensive and do not last long, so you can always target for holiday offers and buy several at a time.