How Many Christmas Lights Can I String Together? - Backyard Boss
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How Many Christmas Lights Can I String Together?

When it comes to Christmas lights, many people that decorate their homes for the holidays have this question: “How many Christmas lights can I string together?” The last thing you’d want to do is accidentally damage your string lights by going over the maximum connectivity rating, or worse, damage your electrical source. Both can be a possibility when dealing with string lights and improper power sources.

But don’t worry! This guide is dedicated to detailing exactly how many string lights you can safely connect together for your upcoming decor project. As long as you can identify the type and wattage of your string lights and the electrical information about your power source, you’ll be good to go.

If you have a great set of indoor or outdoor Christmas string lights and you’re not sure how many you can safely string together, read on to learn how!

Determining How Many Strings of Lights You Can Run Together

So, how many strings of lights can you run together? It’s a very fair question, and the answer can be a bit complicated. You’ll need to consider the electrical components of your power source and the string lights themselves.

how many christmas lights can i string together outdoor tree lighted from below

Find Your Christmas Lights’ Maximum Connectivity Rating

Maximum connectivity refers to the highest volume of strings you can connect in a single circuit. Or, it can be defined as the number of plugs you can stack on top of each other. For example, you may want to connect a number of string lights together so they can stretch across your roof.

The maximum connectivity of your string lights, or the number of lights that can be connected together safely, can be calculated with a simple formula:


Let’s consider an example. Let’s say your string light product has a maximum connectivity rating of 100 watts. Each string light boasts a wattage of 10 watts.

(100 watts/run)/(10 watts/string)=10 strings/run

So, you can safely connect no more than 10 of these string lights together.

closeup of wood with string lights on it

Consider Your Light String or Bulb and Cord Specifications

Every string light you could buy will have a maximum connectivity rating or at the very least details about the product wattage. If the product you’ve purchased does not have this specification printed on the packaging, it may be safer to return it and opt for a different product.

The maximum connection guideline of pre-wire light strings (such as mini lights, craft lights, and LED lights) is usually around 210 watts. The wattage of individual strings are usually quite low, typically between 10 and 20 watts. These lights are ideal to use if you need to string a lot of them together in a serious, as incandescent lights tend to require significantly more power to operate.

REMEMBER: Always identify the wattage of each individual string and look for the UL (Underwriter’s Laboratory) seal with the maximum connectivity wattage of the product. All you need to do is some simple math to ensure you can connect your string lights safely.

Extension lead power strip extension cord

Consider the Electric Service You’re Using to Power Your String Lights

Keep track of the total number of string lights or bulbs you are connecting together, and ensure that they do not exceed 80-85% of your breaker’s wattage. Common home breakers use a general rule to not go over 1400 watts per plug.

If you happen to have a larger breaker, you will have a little more wiggle room– but the only way to really determine the max wattage of each plug is to consult an electrician.

When we say “plug,” we’re talking about “plug per breaker.” Many homes will have multiple outlets on a single breaker, so it’s vital to keep track. Always shoot for a lower wattage to avoid maxing out your breaker.

If you’re dealing with a substantial lighting project, it would be in your best interest to invest the money in an electrician’s visit to make sure you customize lighting work is safe and electrically correct. This would absolutely be worth the investment of $50-$100 for an hour of their time– you could potentially save thousands of dollars in damages with their help. This may not be necessary for small lighting projects, but large theatrical outdoor light projects should always involve an electrician consultation.

how many christmas lights can i string together fire hazard

How to Safely Plug in Christmas Lights

Based on the information we’ve gathered above, let’s look at the step-by-step guide to safely plugging in Christmas lights:

  1. Look for the individual wattage and maximum connectivity wattage of your string lights via the product packaging before purchasing.
  2. Utilize the (watts/run)/(watts/string)=strings/run formula before connecting any of the lights together to determine the maximum number of strings you can safely connect.
  3. Via your home’s breaker, verify the maximum wattage for each plug in your home. (This will usually be around 1400 for the average home.) Ensure that you don’t go over this number. Preferably, you should use under 80% of this wattage.
  4. Account for your extension cords, timers, and any other items that will be connected to your string lights and what kind of wattage they have.
  5. Plug your lights in and enjoy your extended string lights!


christmas lights bokeh purple lights indoors

What Happens if You String Too Many Christmas Lights Together

This depends on how overboard your string-connecting went. If you’ve accidentally gone a string or two over the maximum connectivity rating for your lights, the little fuse that often comes with them will blow. This is designed to happen so you don’t overload and possibly damage your Christmas lights. Many string lights come with spare fuses so you can adjust your string lights.

Some lights, though, may not have a fuse. Connecting too many of them together could result in overloading of the lights, which could cause permanent damage. In a worst-case scenario, particularly for large outdoor lighting projects, you could accidentally blow your breaker. This can be very costly to fix and could also be a fire hazard.

outdoor christmas trees in snow with colorful lights at night

Play it safe! Do the math to find the maximum amount of lights you need and consult an electrician for larger projects. It’s as easy as that!

Connecting string lights together really isn’t that complicated, is it? Drop us a comment below to let us know what you think about this guide!