Christmas Lights Wattage

Does this sound familiar: every Christmas you try to plan your lighting, but find yourself asking, "Why do I keep tripping by circuit breaker?" or "Why do I keep blowing fuses?" Perhaps you are wanting to increase your light display this year, or you are trying to calculate ways to save on power during the holiday season. To help answer these questions and plan a display for a stress-free season, we will walk you through the calculations related to power consumption, and address common amperage capacity issues.

The questions we plan to answer in this resource include:

Electricity Cost Christmas Click here to learn how wattage impacts your electricity bill.

Choose Christmas lights by power

Shop Christmas Lights

  • 5 and 7 watts bulbs
  • Connect up to 10 mini light strings
  • UL Listed

Shop Energy Saving LED Lights

  • 0.069 to 0.96 watt bulbs
  • Connect more - up to 87 strings
  • Reduce energy draw 80-90%

Christmas Lights Wattage and Amps - What Does It All Mean?

Understanding Christmas light wattage and amp current helps to ensure the best Christmas lights display. Wattage has an impact in every area of Christmas lights from planning to installation. Once you can find out your bulb wattage and understand how amperage affects your project, shopping for Christmas lights and customizing light displays becomes a lot easier.

How many watts do my Christmas lights use?

Watts is a measurement of the amount of energy used. Wattage is typically provided per bulb or string, listed on the bulb or near the UL tags on a string. If wattage is not listed on the stringer or bulb, wattage meters are available for around $10 to calculate draw.

An incandescent mini light bulb will use a significant less amount of watts than a larger C7 bulb, and LED bulbs will typically use 80-90% less than their incandescent counterparts.

How Many Watts Per Bulb

When string wattage is not listed but bulb wattage is known, simply multiply bulb wattage by total lights on the string to get total wattage.

How Many Watts

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Mini Lights

LED minis draw only 0.069 watts, while incandescent mini lights draw approximately 0.408 watts.

C7 and C9 Lights

Retrofit C7 and C9 LED bulbs draw approximately .96 watts. C7 and C9 bulbs are available in 5 and 7 watts each.

How Does Wattage Relate to Amp Capacity?

Watts are a unit of energy (or power) used, and Amps are how much energy the watts draw. Amp capacity refers to the total Amps that can be supported.

Amp Capacity in a String determines how many bulbs can be used in a single length of wire. This typically applies when stringers and C7 or C9 bulbs are sold separately and lighting is customizable. All stringers and spools at Christmas Lights, Etc list Amp capacity in product specifications.

Staying within 80% of the Amp capacity of a wire ensures Christmas lights stay lit throughout the season.

Amp Capacity in a Circuit determines how many total watts can be plugged into a full circuit, regardless of how many outlets the circuit contains, or outlet extensions are added. Outlets connected to a single circuit share that circuits Amp capacity, so be sure to also take into account other items running of the same circuit, such as household lamps and electronics.

Staying within 80% of the Amp capacity of a circuit ensures the breakers dont trip.

Calculating Amp Capacity Needs

When using prelamped strings, or Christmas light strings where the bulbs are already secured into the sockets, total Amps is usually listed in the UL tag near the total watts. When total Amps is not already provided, first calculate total watts, and then calculate for Amps.

Calculate Amps by dividing total wattage by 120 volts (US household outlets carry 120 volts)

How Many Lights on a Circuit

How Many Christmas Lights Can I Run off a Circuit?

To answer this question, you will need to look at the circuit breaker box.

What you need to know about circuits:

  • Common household circuits are 15 or 20 Amps
  • Circuit breaker switches will have the current draw capacity listed on or near the switch
    • 15 Amp circuits will support 1800 watts (less 20% is 1440 watts)
    • 20 Amp circuits will support 2400 watts (less 20% is 1920 watts)
  • Most circuits feed multiple outlets. To test which outlets are on each circuit:
    • Turn circuit switches to the off position
      • Note that most circuit breaker boxes have labels for the switches to help clarify which general areas are handled by each circuit. This can help prevent testing on circuits that are not going to be used
    • Individually turn each breaker on and check to see which outlets have power running. Each outlet with power is being operated by the same circuit
  • Additional items may run on the same circuit. Consider their Amp draw when calculating for available amp current

Divide the total wattage of a 15 Amp current (1800 Watts) by the wattage of your Christmas lights. Use only 80-90% of the wattage for best safety practices. View the chart below for amp needs for more common types of light strings:

How Many Lights on a Circuit

*Keep in mind other items such as outdoor Christmas decorations and household items may be plugged into outlets on the same circuit. Be sure to calculate for their power draw.

How Many Christmas Lights Can I String Together?

Christmas Lights, Etc follows UL Standards regarding max strings connected, or how many light strings can be plugged together into a single outlet opening. UL listed lights state a maximum of 210 watts can be connected when using 22 gauge wire, and a maximum of 420 watts can be connected when using 20 gauge wiring.

Mini Lights Lights Per String String Watts Max Strings Connected
Standard Mini Lights 50 20.4 watts 10
Standard Mini Lights 100 40.8 watts 5
Premium Mini Lights 50 20.4 watts 10
Premium Mini Lights 100 40.8 watts 5
Commercial Mini Lights 100 40.8 watts 10
LED Mini Lights
LED 5MM Mini Lights 70 4.8 watts 48
Commercial LED 5MM Lights 25 2.4 watts 175

*20 gauge wire is used in commercial sets

We suggest following max sets connected recommendations for best results.

Note how many more LED Christmas lights can be plugged together. LED lights require only a fraction of the power that incandescent lights draw, consistently resulting in the ability to plug more LED lights together.

How Much Power Can I Save with LED Lights?

LED Christmas lights wattage is significantly less than incandescent lights, and bulbs always stay cool to the touch. LED lights save money both in the power bill, and as an investment: with 50,000+ hours average life versus 3,000 for incandescent lights, LEDs can be reused for years. To read more about LEDs and their benefits, check out the LED Christmas Lights Guide.

Can I Save Power Using a Timer?

Yes, timers help in saving power by scheduling exactly how many hours to run Christmas lights. When selecting a timer, be sure to check for Amp capacity. Note that if you choose a 15 Amp timer and use it with a 15 Amp circuit, that circuit can still only support 15 Amps total - the timer does not add Amp capacity to a circuit, it supports Amp capacity of the lights that are plugged into it.

Easy Formulas for Calculations

Our stringers and spools use UL Recognized components and meets CSA specifications, allowing longer runs of wire than prelamped strings. It is best practice to draw only 80-90% of the rated capacity. Use the following formula to calculate how many bulbs can be used in a single custom run using stringers or spools:

How Many Bulbs Per String

Just in case you missed it above, here is the formula for determining what amp capacity is needed:

How Many Bulbs Per String

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7 Amp Wire

Shop 7 Amp Wire

7 amp wire is ideal for shorter runs and low watt LEDs. Choose from a variety of color and spacing options.

10 Amp Wire

Shop 10 Amp Wire

10 amp wire offers higher amperage for long runs of light, and is ideal when using C9s. SPT2 wire offers best insulation.


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