There’s a ton of web sites out there offering all the same basic advice on Christmas light safety; don’t use frayed cords, don’t use damaged lights, etc. I think most people have this basic knowledge of Christmas Lights 101. I was curious what could really pose a threat if you’re using new lights and new extension cords, so I thought I’d do a little math and figure it out.
There are three main places for potential failure when installing Christmas lights – extension cords, power strips, and light cords. I’m assuming the lights will be plugged in to a standard 15 amp outlet, and nothing else is running on that circuit (lighting, TVs, radial arm saws, etc).
Lights: I took a brand new string of 150 lights and examined the fine print on the warning label. The lights draw .54 amps. This means that you could theoretically have 27 sets of lights plugged in to one circuit, and you would use 14.58 amps – just below the tripping point of a standard 15 amp breaker. Each string of lights has a 3 amp fuse built in to the plug, so you could potentially have five strings of lights plugged in to each other, end to end, to get 2.7 amps. For the record though, I’ve always heard that you shouldn’t use more than three.
If you notice the date code on lights, you noticed more than the average person does. Most lights have been sitting in attics and closets for years. When lights and decorations go on clearance, most people buy for the next year to just leave in storage.
Power Strip: I just took a look at a cheap power strip that I had lying around in my garage and was surprised to see that the power strip was rated for 15 amps! This means in theory that the power strip should be able to deal with anything I plug in to it – if I overload it, the circuit breaker in my electric panel will trip.
Extension cord: I expected this to be the weakest link, but it’s not as weak as I thought; the smallest extension cord I could find online or in the store was rated for 13 amps. This means that if you plugged a power strip in to the end of the extension cord and ran 5 strings of lights (with 5 sets to a string), you would have a total of 25 sets pulling13.5 amps. This could start the extension cord on fire. Twenty-four sets of lights would probably be safe at 12.96 amps, giving you a total of 3,600 lights. Most fires are started by improper use and overuse of an extension cord.
The bottom line? All the advice you hear/read on basic light 101 is right on. As long as you’re using new lights, new extension cords and new power strips, you shouldn’t have much to worry about, and you shouldn’t have to do any math. Just remember to read the safety labels and do some simple calculations if you think you’re using too many lights.
What if 3,600 lights isn’t enough? LED lights are a great alternative. They’re initially more expensive, but they use 80% – 90% less , saving money in the long run
What about the heat from the lights? Mythbusters already tried setting a Christmas tree on fire using only the heat from the bulbs and found it was impossible. They ended up using a neon transformer to set a tree on fire.
But all of this just means to keep the basics in mind. Check and double-check your power strips, extension cords and the age of your lights. Do not go overboard like the Griswalds in Christmas Vacation. Safety of your house and family first to have a Happy Holiday Season!