How To Wire Outdoor Christmas Lights

When Christmastime comes, the outdoor lights come out all across the United States. Though these lights look the same as the string lights used to wrap a Christmas tree or decorate the interior of a home, outdoor Christmas lights are made to endure cold winter temperatures and moisture from rain, snow, and ice. In order to keep your outdoor Christmas lighting display safe for your home, you should also keep outdoor conditions in mind when wiring your lights.

Before you put a bunch of boxes of Christmas lights in your shopping cart, figure out how many feet you’ll need. Make sure to think about every place you want to light up. You can use string to measure spiraling places, like the columns on your front porch. Don’t forget to measure how far away your nearest grounded outdoor outlet is and make plans based on that.

Safety should be foremost in the wiring of outdoor Christmas lights. And this is how to wire outdoor Christmas lights like a pro.

Step 1

Find an electrical outlet in or around your home where the wires will be out of the way of everyday traffic. Plug in a surge protector or another electrical outlet receptacle to the outlet and note the maximum amps recommended for the receptacle.

Step 2

Run extension cords from the power receptacle. Make sure you get insulated extension cords recommended for use outdoors and plug in only as many extension cords to reach the receptacle as the receptacle can handle. For instance, if you have 13-amp extension cords and the power receptacle can handle only 15 amps, you can plug in only one extension cord per receptacle.

Step 3

Figure out how many Christmas lights you can string together and plug into each extension cord. Calculate the number of lights an extension cord can handle based on the amperage of the lights. According to All American Christmas Company, light strands with 25 bulbs run between approximately 1.1 and 1.6 amps; strands with 100 bulbs run between roughly 4.5 and 6.4 amps, depending on the type of bulb.

Step 4

String together only the number of lights that each extension cord can handle to plug into each extension cord. If you have 50-bulb light strands at 2.3 amps apiece, for instance, you can string five strands of light together to plug into a single 13-amp extension cord.

Before wiring your outdoor Christmas lights, you must know the distance that each cord must reach. To determine this, measure the distance from the electrical outlet you want to plug the lights into to each spot in your yard that you want to light. When measuring, run your measurements down walls and across the floor and the ground, and then add a foot to each measurement to ensure you have enough slack in the cord. The amperage of each strand of Christmas lights should be listed on the packaging.

Common questions about hanging Christmas lights

For the average homeowner, what are the most common types of Christmas light installations?

I think most people like to put lights in their trees and bushes and on their porches. Others will put lights along their roof edge.

I see a lot of spectacular displays where homeowners have wrapped their trees (trunks and branches) in Christmas lights. I really love the way this looks, so I tried to do this last year without much success. My wraps were uneven and began to sag in many places, and it just didn’t look professional. What is the best approach to doing a tree wrap installation?

There are many different theories on how to do this, so I will give you mine. I would start at the bottom of the tree and work towards the center or crotch. Wrap around the tree trunk tightly and try to space the lights evenly as you work your way up. Once you get to the center (crotch), you will have many branches you will have to wrap. What I do is wrap the branch half as dense as I want it as I work my way up, then when wrap it back towards the center to get the full light density that I want. Then I move on to the next branch and repeat the process. You should end in the center when done. Don’t be afraid to use a zip tie to hold lights in place on those tricky spots. By wrapping a tree this way, you will be able to hook all the lights together using only one extension cord. Of course, you have to follow UL guidelines for the number of sets you can hook together.

I’ve also seen many fantastic displays where the homeowners have hung Christmas lights all along their rooflines or eaves. (I haven’t dared try this on my house because of the pitch of the roof…) Although I have never tried this myself, I’ve seen some displays that look great and others that look sloppy. The ones that look great have perfectly spaced lights that extend across the roofline on an even plane. The ones that look bad don’t even have spacing, and the lights are out of line. What is the best way to do a roofline installation?

The best way is to have a Christmas light clip for each light. If each light is clipped to your roof, you will have a nice clean straight line with no sagging. (It will be as straight as your roof.) You’ll want to pull the light strand almost tight to have a nice even spacing. There are several clips on the market that will work for both gutters and shingles.

Many people have bushes, shrubs, or hedges around their entryway or in other locations they would like to add some holiday color. The displays I have seen have been all over the board–some people will try to wrap the bush horizontally; others will install the lights in vertical lines on the face of the shrub, and others (like my friend’s dad) seem to have just thrown them on. I’ve never figured out the best approach to this. Do you have any suggestions?

The trick here is taking your time. Personally, I like to put lights in horizontally, although going from top to bottom will work as well. I would start at the bottom edge and work to the other side. Then you loop back toward where you started. You keep going back and forth until the bush is fully covered. The trick is to have your spacing correct. If you are using lights that have 4-inch spacing, you also need to make sure your loops are about 4 inches apart as well. This will give you a nice full-looking bush where the lights look evenly spaced. Make sure you stand back 10-20 feet to see how it looks, and then make adjustments if needed.

Mas Broto

Written by: Mas Broto

Mas Broto is a small business owner with 30 years experience in the real estate industry. He is the founder and editor of, the most comprehensive free home improvement website on the planet!