How to Calculate the Voltage of Christmas Lights
Christmas lights use very little power. Mini-bulbs, small incandescent bulbs, have been in use for years and a string of them use about the same power as a normal light bulb. LED lights are becoming more common as well, and they use as much as 98% less power than mini-bulbs. To calculate the amount of power used, it is necessary to know a little about electricity measurements and terms.
Volts, Amps, and Watts of Christmas Lights
In the US, the standard power from an outlet is 120 volts. Traditionally, a string of 48 mini-bulbs uses 2.5 volts. 48 times 2.5 equals 120, and so it logically follows that a single strand will equal the standard number of volts from an outlet. Now it is common, however, for there to be 50 bulbs, which just means the voltage is spread a little thinner. Each one uses a tiny bit less power and is imperceptibly dimmer. Voltage is like water pressure in a pipe; the more area it’s required to cover, the less there will be for each fixture.
The amount of power of an electrical object is measured in watts. Multiply the wattage of each bulb by the number of bulbs on the string to get the total power required. Dividing that number by 120 volts results in the amount of current, or amps, needed for the lights. Amps are the amount that flows through the pipe.
Calculating the Voltage of a Strand of Lights
Most strands should be labeled with what their voltage is, but over the years, tags can fall off or the information can get worn away. After all, Christmas lights are not particularly expensive products. But now that you have the basic idea of how electricity works for Christmas lights, you can use the principles of calculating voltages on any strand you might have.
First, you’ll need to know how many lights are in your strand. This should be easy since most strands come in even numbers like 50 or 100. So, if your outlet is 120 volts, and you have a strand of 100 Christmas lights, all you have to do is divide 120 by 100 to get the approximate voltage of about 1.2. As we saw in the earlier example, this isn’t entirely exact all the time, but it will definitely give you a good starting point.
LED Lights
These lights use so little power that worries about the amount used aren't really necessary. However, the same principle as above applies.
-
![Doityourself Staff]()
![H.R. Helm]()
H.R. Helm is an accomplished DIY craftsman. He has been DIY since childhood and is now a septuagenarian. He is experienced in wood and metal construction, having designed and built several houses and metal buildings. He built every permanent building on his current homestead and did all the plumbing and electrical work. He has several years experience as a professional cabinet builder, and he is an accomplished auto repairman, having operated an auto repair business for many years. He currently has a home shop where he sharpens and rebuilds saws, repairs lawn mowers, mobility scooters, hydraulic jacks, and anything else that comes along. He also builds custom tools for metal working. Invention prototypes are another of his many accomplishments. He owned and operated a manufacturing business building Compact Utility Vehicles for homeowner use. H.R. enjoys making jams and jellies during fruit season along with cooking meals. He is committed to outdoor cooking in a Bar-B-Q pit he welded together several years ago. He maintains fruit and nut trees along with helping his wife with a vegetable garden. He farmed commercial garden produce for several years. It helps to have over 50 years of farming and ranching experience. Employment/Education Highlights ASE Certified Master Auto Technician Certified Welder Cross country truck driver -- over dimensional freight Design Engineer/Project Manager for injection molded plastic company Bus Driver/Substitute Teacher Inventor with two patents (weight training – anti-rollback for manual wheelchair) BS in Industrial Technology
