how to know if christmas light fuse is blown

To determine if a Christmas light fuse is blown, check for one of the following signs: The lights in your Christmas tree won't light up at all. The strand of lights has dark spots on it, indicating that some bulbs are not working. Some lights in the strand are flickering or dimming. You can also check by plugging the strand into an outlet and using a voltage tester to check for a flow of electricity. If there is no flow of electricity, then the fuse is likely blown.