How much power do I need to run my Christmas Lights?

Posted by on 11/1/2015 to Troubleshooting Your Christmas Lights
How much power do I need to run my Christmas Lights?

How much power do I need to run my Christmas Lights?

Before you get ready to plug in your Christmas lights this year learn how to calculate the power needed to run your amazing display.  So what do you need to know to get started? First things first, you need to know the wattage of your Christmas lights, the Amps your lights use,  the circuit breaker size on the outlets you will be plugging them into and you need to know the voltage of the outlets.

Check your Voltage on your outlets and your Christmas Lights

In the US a standard household outlet runs on 120 volt power. The standard circuit breaker size is generally 15AMP and often controls multiple outlets in a house or outside. Standard Christmas Lights in the US are generally 120 volt so just make sure what you purchase matches the voltage you have available. Some commercial properties or boats use 12 volt power and so you will need to match the voltage to your Christmas lights to have them work properly.

Check your circuit breakers Amps

Standard US household circuits generally run on 10, 15, 20 or 30Amps.  The average is a 15 Amp circuit breaker.  This tells you how many Christmas lights you can have going to that circuit breaker.  Your 15 Amp circuit can handle up to 1440 watts of power.  Make sure you know what other items may be plugged into the circuit before you overload it. We had a house once that had the outdoor outlets wired on the same circuit as our bathroom power outlets so anytime we used indoor small appliances like a blow dryer when the Christmas lights were on we tripped the breaker! So annoying, it took some time to figure out where the correct GFI to reset the circuit was.  

Check the wattage of your Christmas Lights

  • Standard mini Christmas lights use 40.8 watts of power per strand of 100 bulbs. 
  • Standard C7 Christmas lights use 5 watts per bulb or 500 watts for 100 bulbs.
  • Standard C9 Christmas lights use 7 watts per bulb or 700 watts for 100 bulbs.
  • High quality LED mini Christmas lights use 4.8 watts for a strand of 50 bulbs.
  • 3 diode C7 LED Christmas lights use a little less than .6 watt per bulb or 60 watts for 100 bulbs.
  • 5 diode C9 LED Christmas lights use 1 watt of power per bulb or 100 watts for 100 bulbs.

Now calculate your total power needed

If you donâ€â„¢t want to end up like the Griswoldâ€â„¢s you need to know exactly how many strands you are using and plugging together. UL rating suggests you should use no more than 210 watts end to end on traditional mini light wiring (22AWG), this is generally 5 strands of 100 mini lights. If it is 20AWG wiring this rating goes up to 420 watts. If you are using C7 we recommend using no more than 100FT end to end, but you can put up to 288 standard 5 watt bulbs on a 15 amp circuit (again, follow the rule of using no more than 1440 watts of power on a 15 amp circuit).

If you have a dedicated outdoor circuit for your Christmas lights with a 15 Amp circuit breaker you can put 1440 watts of lighting on this circuit. This will allow you to use approx. 100FT of C7 light line on your roofline and an additional 22 strands of mini lights on trees, shrubs or bushes to decorate your house.

If you are ever in doubt, please contact us to get power recommendations on your project.  As commercial decorators we understand power needs and can give you suggestions and ideas to decrease the power needed without sacrificing the look of a beautifully decorated property for the Christmas season.

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