How Many Christmas Lights Can I String Together

Don’t blow the circuit breaker or the in-line fuses. Learn how many strands of Christmas lights you can safely string together, with help from Mr. Electric.

Last updated: 9/12/2023

At Mr. Electric, one of the most common holiday questions we get from concerned homeowners is, “How many lights can I string together?” Hoping for an easy rule-of-thumb, it’s easy to become frustrated by the answer, “It depends.” Considering the vast differences in power consumption between LED and incandescent string lights, however, the reason for this answer quickly becomes clear:

  • LED Holiday String Lights
    LED lights cost more, but if you strung a whopping 265-feet of strands together, they’d use just 38-watts and could be plugged into a single outlet, costing a little over $1 in electricity for the season. Using about 1/10 the wattage of incandescents and lasting 10-times longer, they’re a whole new holiday animal.
  • Incandescent Holiday String Lights
    Prefer less expensive incandescent strings? A comparable lengths worth of incandescent string lights would consume a whopping 1,925-watts, each individual string requiring its own outlet. And all that money you ‘saved’? Plan to spend it on electricity: Over $50 worth for a season of festive flair.

So, How Many Christmas Lights Can I String Together, Anyways?

Not worried about efficiency, simply logistics? Before you start blowing circuit breakers or in-line fuses, learn how many strands of Christmas lights you can safely string together no matter your light bulbs style with the help of these holiday string light safety tips from Mr. Electric:

  • Determine Maximum Load
    Decide which circuit(s) you’ll be plugging holiday string lights into. Find that breaker on your home’s electrical box, noting whether it is a 15 or 20-amp circuit. No matter which light style you string, you should never exceed more than 80% of circuit capacity. This will prevent the need to rectify frequently tripping breakers and help you avoid overheating wires and fire danger.
    • 15-amp circuit: Max 1,440 watts (80% of 1800 is 1,440).
       A 15-amp circuit can handle 1800 watts (15 amps x 120 volts).
    • 20-amp circuit: Max 1,920 watts (80% of 2,400 is 1,920).
      A 20-amp circuit can handle 2,400 watts (20 amps x 120 volts).
  • Figure Out What Other Home Items are Running on that Circuit
    Any other items running on that same circuit, from lighting to appliances, should also be counted as part of the 80% max circuit load. (This is why a separate, dedicated circuit for holiday lights is best, making the math simpler, and allowing you to put outlets exactly where you need them, with fewer extension cords.)
  • Look for the Wattage of Each String of Lights
    The UL (Underwriter’s Laboratory) has already done the math for you. Look for it on the tag on your string lights or on the box, which will also often indicate the number of lights that can be safely strung together, limiting the need for brain-melting holiday math endeavors.
  • Heed the Warning
    All UL tags state not to exceed a maximum of 210-watts. (With LED lights you typically won’t have this issue, as they use such little energy.)
  • Grab a Calculator
    Divide 210 by the number of watts each string uses, and this will give you your number of strings you can successfully daisy-chain per outlet. For a 20-watt strand, that’s 10.5 string lights connected in series. Don’t forget to sum the wattage you’re plugging into each outlet on the circuit, making sure not to exceed maximum wattage (1,440/1,920).
  • Start Stringing

Avoid any hair-raising Griswold-style electrical antics. Deck the halls with flickering lights – not the flickering flames of an electrical fire. Contact Mr. Electric for help stringing those holiday lights today.

This blog is made available by Mr. Electric for educational purposes only to give the reader general information and a general understanding on the specific subject above. The blog should not be used as a substitute for a licensed electrical professional in your state or region. Check with city and state laws before performing any household project.