Can I mix incandescent and LED Christmas lights?

March 13, 2014

This is a tricky question because the answer depends on what type of lights your are looking at.

String Lights

(with series wiring – ie. mini lights, craft lights and pre-wired LED string lights)

For string lights, it’s important to stick with one family of lights in series because LED and incandescent lights pull vastly different amounts of current.  (If you think of electricity as a river, current is a measure of how much water is flowing.)  LED’s only need a little current and if you run them in series with a much higher resistance traditional string of mini lights then you run the risk of damaging your lights or worse, starting a fire.

It’s a good idea to only run string lights in the same family together in one run.  Only LED’s in a run or only traditional lights in a run.  When it comes to traditional lights, it’s best not to run lights of various number of bulbs together in series but stick to running lights with similar characteristics in single runs.

Socket Wire with Separate Bulbs

(With Parallel electrical connection)

Traditional socket wire with heavy duty wiring is generally wired in parallel.  All of the stringer cord that we carry is wired in parallel.  This means that the electrical current is delivered to each bulb on the circuit in only the quantity that it needs.  (Constant voltage, variable current for those of you who want this in techno-speak.)

Your can see examples of these types of stringers at C7 cords and C9 cords.

Because these cords are wired in parallel, you actually can run traditional incandescent or filament bulbs in the same run as LED bulbs.  You could alternate painted blue or opaque bulbs with LED bulbs for different textures in your lighting.

Aside from style considerations, also keep in mind that even though you might use a large number of LED bulbs, the longest run of stringer wire that you can safely operated cannot exceed the maximum length rating of the cord itself.  LED bulbs don’t carry much current but if 18 AWG wire is run too long, it can act like it’s own fuse and you can blow your breaker or worse start an electrical fire.

For 18 AWG wire, we don’t suggest any run longer than 250 feet.

Ultimately, if you are running custom lengths of cords together in series, consult with a master electrician to confirm your wiring is safe and within the specifications of your materials.

If you choose to go all incandescent keep in mind that C7 and C9 bulbs range in wattage from 5 to 10 watts.  We suggest that you don’t exceed 1000 watts per breaker.  Again, consult with a local master electrician.

Well, I hope that this answers your questions.  If you have any technical questions, please contact an electrician or if your question is related to a product, please contact us at Contact Page.

12 thoughts on “Can I mix incandescent and LED Christmas lights?”

  1. I have a playhouse that I’m decorating like a gingerbread house. I’m using 4 strings of c7 LED lights around the roof plugged into one extension cord. I’m also using a string of older, candy cane lights plugged into a separate extension cord. My question is, can I plug both cords into the same outlet?

    1. Yes, you can plug them into the same outlet. (As long as their total power requirement doesn’t exceed that of the breaker. What you describe sounds like it will be fine. Add up the wattage of the strings and make sure they don’t add up to be more than 1000 watts.)

      In the scenario you describe it sounds like they aren’t plugged into one another which is what we want to avoid.

      If you have additional electrical questions, give a quick call to your neighborhood electrician.

      Sounds like a fun project. We’d love to see photos.

      Shellie

  2. I have a 9ft pre-lit Christmas tree I bought last year. The bottom row of lights went out and all the bulbs were burned. It was obvious something happened which required all the bulbs be replaced.

    I tried using LED lights from another strand of working lights (without realizing they were LED) to replace the ones that were out. I quickly realized that they didn’t light the same way and determined they were LED. So, I went and bought 7volt bulbs that the Walmart worker said would work on any normal tree. (Talk about the blind leading the blind.) I put on 80 7v lights before I realized those were too strong for my 2.5 volt tree!! So, I went out and bought the correct replacement lights and began the daunting task of replacing the entire bottom section of lights.

    NOW, that the lights are working, I’m noticing that one section is extremely bright even though most of the lights are the correct 2.5v. I’m sure there are some bulbs that don’t belong. Also, the strand next to that section is unusually dim and some lights are almost going out, they’re so dim.

    What on earth did I do!? I’m typically pretty quick (smart and thoughtful) but this whole endeavor was a huge FAIL. I’ve certainly learned a lot but I need to learn more! Help!

    1. It sounds like you still have a variety of differently rated bulbs on that string. This is more than likely what causing the uneven brightness on that single set and affecting how much current is reaching the other sets.

      Unplug the defective set to see how the other sets respond. Consider plugging all of the lights that were fine into another extension cord while you work on or replace the set with issues.

      It’s going to be hard to differentiate which bulbs are not the correct voltage rating since they probably look very similar except for those LED bulbs. Make sure all of the LED bulbs are removed and replaced with bulbs that are the correct voltage for your light string. Check for tags next to the plug to see if they include the replacement bulb voltage specification. You might also check the box the tree came in or find the tree online (if that’s how you purchased it) to see what the specific bulb rating is for those lights. Lights that are custom made for pre-lit trees are not necessarily standardized.

      If you don’t have that exact correct replacement bulb voltage, you may need to consider replacing that last set. Varying voltages and the issues you are describing may pose an electrical risk.

      Good luck with your project. That’s a really lovely tree. 🙂

  3. I have a 9ft pre-lit Christmas tree I bought last year. The bottom row of lights went out and all the bulbs were burned. It was obvious something happened which required all the bulbs be replaced.

    I tried using LED lights from another strand of working lights (without realizing they were LED) to replace the ones that were out. I quickly realized that they didn’t light the same way and determined they were LED. So, I went and bought 7volt bulbs that the Walmart worker said would work on any normal tree. (Talk about the blind leading the blind.) I put on 80 7v lights before I realized those were too strong for my 2.5 volt tree!! So, I went out and bought the correct replacement lights and began the daunting task of replacing the entire bottom section of lights.

    NOW, that the lights are working, I’m noticing that one section is extremely bright even though most of the lights are the correct 2.5v. I’m sure there are some bulbs that don’t belong. Also, the strand next to that section is unusually dim and some lights are almost going out, they’re so dim.

    What on earth did I do!? I’m typically pretty quick (smart and thoughtful) but this whole endeavor was a huge FAIL. I’ve certainly learned a lot but I need to learn more! Help!

    1. It sounds like you still have a variety of differently rated bulbs on that string. This is more than likely what causing the uneven brightness on that single set and affecting how much current is reaching the other sets.

      Unplug the defective set to see how the other sets respond. Consider plugging all of the lights that were fine into another extension cord while you work on or replace the set with issues.

      It’s going to be hard to differentiate which bulbs are not the correct voltage rating since they probably look very similar except for those LED bulbs. Make sure all of the LED bulbs are removed and replaced with bulbs that are the correct voltage for your light string. Check for tags next to the plug to see if they include the replacement bulb voltage specification. You might also check the box the tree came in or find the tree online (if that’s how you purchased it) to see what the specific bulb rating is for those lights. Lights that are custom made for pre-lit trees are not necessarily standardized.

      If you don’t have that exact correct replacement bulb voltage, you may need to consider replacing that last set. Varying voltages and the issues you are describing may pose an electrical risk.

      Good luck with your project. That’s a really lovely tree. 🙂

  4. I have several “older” strings of lights/decorations
    and now have a few new LED decorations ALL
    plugged into one electric strip. Some of the older incandescent decorations went “dark” the second I flipped the strip on. Why???

    1. Wow – that is really unusual. Did you try plugging them in by themselves?

      It sounds as though too many of them were plugged in end-to-end and you might be looking at an issue of blowing the fuses. Or the power strip might need replacement.

      It’s hard to say but these might be a couple of first things to consider.

  5. I’m having some real frustrations with ~80 ft of C9 incandescent bulbs. Replaced fuses first, but that burnt out. Noticed that 2 of the lines had 10 A fuses while the other 2 had 5 A fuses, so I swapped out the 5 A for 10A fuse stringers. Worked, but then the whole line went out again. Am I putting too much current through the lights? Would swapping in some led C9s drop the current draw to a manageable level for the fuses? Ive confirmed voltage is being delivered to the line, so the problem has to be with the light setup as opposed to the circuit breaker…

    1. The manufacturer chose the 5-amp plug based on the electrical specifications of your cord. It sounds like you have overloaded your cords or they have become damaged over time. I would reboot with a new cord instead of putting your investment in LED bulbs at risk.

  6. Can I connect LED icicle lights to the end of my incandescent c7 string and plug them all into one plug

    1. No, run a second extension cord, the higher current of the C7 string will damage your LED icicles.

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