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Christmas lights aren't working :( Answered

I have a small set of Christmas lights that will not come on. With my multimeter I tested the fuses, several light sockets (the one closest to the plug, the one furthest away, and one closer to the middle), and the female plug on the end. I'm getting 120v coming out of the female plug, the sockets are providing between 2v and 4v, and the fuses provide almost no resistance, and the filaments are visibly intact.
What's wrong?


It's possible that one or more bulbs' contacts are not making contact with the socket. Most sets require that all the bulbs be inserted correctly for the set to light.

When I run into that problem. I pull each bulb, make sure that the wires are correctly positioned, and reinsert them. Inevitably, one has a wire that has somehow gotten bent out of whack, so the circuit isn't completed. I don't think that 120VAC on the outlet socket at the end of the string is sufficient to assume the bulbs are inserted the right way.

Absolutely correct. Modern light sets are wired so that if one bulb blows, the rest will stay lit, including any additional sets plugged into the female connector, so power at the far end is to be expected, even if the bulbs aren't lit. Removing and reinserting each bulb is the only way to figure out where the problem is, unless you have some kind of specialized light string checker device.

exactly. it defies common sense, but even when a bub has burned out,as long as it's inserted correctly, the rest of the set will still  light.  "Correctly" is the key.

Like everyone else says, you have to test each bulb until you find the problem, and if the problem can be fixed, then do that. How old are they? My Christmas lights are about ten years old and I had to get some more because a string went out. If they're older, then it might be a good idea to buy a new, more modern string that doesn't need all the bulbs to work to complete the circuit.

You have to test every electrical connection on the string of lights. Pull all the light bulbs out and test them, it is highly unlikely that there will be a problem with the strings itself.

If these are strung in series (as it sounds) it'll probably be just one bulb / connection. Find a method to identify that one. E.g. Test half way, one side should be connected, the other not. Halve it again, and again etc.