First steps
Identify the type of light string you have.
You are currently viewing information for traditional incandescent Christmas string lights. For LED lights, please refer to LED Christmas Lights.
Introduction
Incandescent Christmas tree lights are typically organized in a series circuit. This means that each light is connected directly to the next one in the string.If a bulb becomes even slightly disconnected, falls out, or if the wire at the bottom of the light is damaged, the circuit will be broken. Consequently, none of the lights on that circuit will light up.
If you find only a portion of the lights in your string are not lighting up, it is likely that your light string has more than one circuit. Manufacturers do this so that if one of the circuits is broken, your whole line doesn’t go out.
Note: Bulbs have a small wire that keeps electricity flowing if they burn out. If only one bulb is burnt out, replace that single bulb.
Causes
If your entire string light is out, it is possible that your fuse has blown.
- Refer to the video below to find and learn how to pull out your fuses.
- Inspect the fuses. Intact fuses have a filament running the length of the clear tube. If the fuse is blown, the filament will be broken and the inside of the tube may be discolored.
- Replace blown fuses.
You will need to find the problematic bulb by going through the unlit lights one by one inspecting and testing each light.
Check for the following in every socket.
Bulb is not placed in socket correctly
It is possible that the bulb has come loose enough to break the circuit. Simply removing and firmly replacing the same bulb will reconnect the circuit and fix your light string.
Wires at the bottom of the bulb are misaligned
The wires at the bottom of the bulb are specifically oriented to allow the in and out flow of electricity. If the wires are not oriented correctly, the circuit may be broken.
When you remove the bulb from its socket, inspect the wires at the bottom. You can easily adjust the wires with your fingers so that they are oriented correctly. CAUTION: Do not adjust live wires with your fingers. This direction specifically applies to the wires at the end of a disconnected bulb.
Bulb is broken - cause not visually obvious
The bulb itself may be broken in a way that is not clear to you. If this is the case, the only way to know is by trying a known working bulb. Get a working replacement bulb and plug it in to the socket of the bulb you are testing.
If it lights up and fixes the string, you are finished. If it does not, continue testing each unlit bulb until you find the one that closes the circuit.
2 common problems
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