Fix Your Old Christmas Lights

Save some money by re-using your existing strings of light this Christmas—even if they’re currently acting all wonky. Here are some handy guides on how to repair dark strings of Christmas lights, whether they’re LED or the classic incandescent type. They’re fairly detailed, with a sort of techy “how things work” vibe, but contain a lot of useful information. For example, just because a string of incandescents has an AC outlet at the end, that doesn’t make it an extension cord—the more power you pull through the cord, the greater the current and the higher the risk of shorting out bulbs.

The author also talks about the LightKeeper, a $15-35 device (depending on whether it’s the “pro” version) that helps quickly locate burned out bulbs in instances when the entire string is dark. If you’ve ever spent a half hour methodically removing and replacing each bulb in turn, you can probably understand why this excites us—even though by buying it you’ve sort of ruined the whole “saving money” aspect of this endeavor. But hey, you still get to be a handyman.

“Christmas Lights and How to Fix Them” [Cyphersbyritter via Make]
(Photo: Scurzuzu)


Edit Your Comment

  1. B says:

    Spend 15-35 on a device that helps you fix lights that cost on 6-10 per string? Sounds like a bargain. Also, if you have non-LED that aren’t working, replacing them with LEDs will pay off pretty quickly.

  2. mexifelio says:

    Lets all be conservative and change our bulbs to compact fluorescent to save energy. Oh wait, here comes Christmas as another excuse to be wasteful and burn up electricity so that … our house can look pretty at night? *sigh*

  3. balthisar says:

    @mexifelio: Christmas is for atheists, too. You don’t have to be a wet blanket.

  4. Spamwich says:

    People still use those old strings that are wired in series? Wow, I thought I was old school because I still had a couple incandescent strings lying around. :)

    @balthisar: I don’t think you have to hold any particular beliefs to find modern Christmases more than a little wasteful.

  5. While I decorate the inside of my house colorfully, I keep my outside display to white lights on the rails and gutters of my white porch, some garland on the two main beams next to the stairs up to the front door, and non-lit fake wreaths on the doors. Inside gets the color treatment(as much as my cats will allow).

  6. mungojerry says:

    My neighbor bought a new indoor (artificial) tree that came pre-wired with lights. Set it up, plugged it in, and lo and behold, a section of the tree was dark. He whipped out the LightKeeper and scanned the bad section and found the dead bulb while looking like a hero!

  7. scoosdad says:

    “..the more power you pull through the cord, the greater the current and the higher the risk of shorting out bulbs.”

    That’s just plain false. If the string has an outlet on the end, that means the lights are wired in parallel across the length of the two conductors of the cord, and not in series.

    If the lights were wired in series (that’s the pesky type that if one bulb goes out or is taken out, the rest of the string goes out too), then the current would flow through each of the the lamps, and there would be no outlet on the end since the lighting of the string depends on a continuous loop from the plug, through all the bulbs, and back to the plug again. An outlet on a string like that would interrupt the flow of current through the lights.

    But if the lights are wired in parallel (that would be a string that lets you completely take out any bulb and not affect any of the others), then any current pulled through the string to the outlet on the other end just flows through the wires between the plug and the outlet, and not through the bulbs themselves. At that point it’s the gauge of the connecting wire between the plug and the outlet that governs how much current you can safely draw through that string of lights.

  8. scoosdad says:

    I should add that if a series wired string has an outlet on the end (and I think most of them do these days), the current to the outlet from the plug does not flow through the lamps, it travels on separate wiring from the plug by itself.

  9. scampy says:


    I am actually much more old school than that. I use Edison bulbs on my tree. I actually collect Christmas lights from 1908 to about 1980. I refuse to use these new crappy mini lights and LED lights. Its getting much harder to find Edison Christmas bulbs but nothing comes close to the look of the nipple bulbs with carbon filaments glowing

  10. scampy says:


    I curse the day prelit trees were invented. I needed to get a new tree this year and it was almost impossible to find an atificial tree that WASNT prelit. I HATE those things. Youre stuck with those crappy mini lights and you cant change the lights from year to year, plus they are the cheap crappy Chinese lights that only last 1 or 2 years

  11. Half Beast says:

    That’s one thing i love about living in an apartment. None of this light strand nonsense. All I have to do is wrap my door up all pretty-like, slap on a huge bow, and 15 minutes later, I’m the epitome of the holiday spirit. A bigger baby Jesus than ODB.

  12. Danny Staple says:

    I managed to fix my lights pretty quickly without a LightKeeper. Although it might be handy, it is quite pricey. I found a really quick way to find the broken bulb in a long chain of lights though – HOWTO Fix Broken Christmas Lights Quickly.