Q&A for How to Replace a Fuse on Christmas Tree Lights

Start by checking the outlet that the Christmas lights were plugged into to make sure there's power present. If the outlet isn't the issue, use a multimeter to test the fuse for continuity. If the meter reads open, you can know for sure that the fuse is blown and should be replaced.

Then the product most likely does not have a replaceable fuse. Not all products have this feature. However, do look carefully, because some products use only a single fuse, and the door may be smaller.

Try using a pair of pliers to straighten out one or two bends in a paper clip, then create a short (~1/16th inch) hook, bent to about 90° at the end. Work it into the fuse recess until you can hook the far end of the fuse and pull it downward and outward. This won't be as smooth as it sounds, but persistence will eventually pay off. Try not to break the glass in the fuse. But if you do, it will probably make things easier. Just be sure to get all of the old fuse (including the second metal cap and the small pieces of glass) out before inserting a new fuse. It may take a magnifying glass, but one of the metal caps should have the fuse's rating (Voltage and Amps) stamped into it.

You can find them most places the lights are sold, such as Target and online. Before buying new fuses, check to see if a small bag came with your lights; manufacturers usually supply spare bulbs and fuses.

Such lights tend to be connected sequentially. Probably one of the lights is broken and interrupting the circuit. Try checking every light and replacing broken ones.

It depends on the exact lights you use. I would check the tag on your lights (if there is one).

There is no such thing for this type of fuses; they work either way.

Toss the complete set, as that is a potential fire hazard and not worth the risk. Buy a new set, they're not that expensive.

Buy a LightKeeper, look them up online. They have one for incandescent and one for LED.

That is not a problem. The "120 volts" is a nominal voltage and may vary from 115 to 125, but 120 was adopted by some standards as the "reference". At least you know it is not some other range such as 208 volts or 240 volts.

You'll find one at a hardware or home-improvement store. Otherwise, try Amazon or eBay.

There is no wrong way to insert the fuse as long as the metal on the fuse touches the contacts. Fuses contain a small wire that breaks when too much current flows through them in either direction, acting as a safety component in the circuit.

A common issue is that one or two of the light bulbs are broken or have a short fuse.

Most Christmas lights come with small cylinder-shaped fuses that can be replaced in a compartment in the plug. Remove the old fuse and replace it with a new one. It does not matter which way you insert the fuse.

It doesn't matter which direction you install the fuse in a DC circuit; it will work either way. However, it's best to place the fuse on the side that offers the most protection and close to the power source to minimize potential damage.

If you've checked each LED, the issue may be with the LED holder or the wire. Examine the holders for corrosion and clean them with a toothpick and fine sandpaper. Once the holders are clean, ensure you re-insert the LEDs with the correct polarity.

Replace the suspected fuse with a new one and test the lights. Depending on the type, you might be able to visually inspect the fuse to see if it is blown.

Plugs for appliances rated up to about 700 watts should have a 3-amp fuse, which is typically colored red.

It's normal for the metal cap to come off. In my experience, it's not dangerous, but you should replace the fuse to ensure proper functioning.