Christmas lights (also sometimes called fairy lights, twinkle lights or holiday lights in the United States) are strands of electric lights used to decorate homes, public/commercial buildings and Christmas trees during the Christmas season. Christmas lights come in a dazzling array of configurations and colors. The small "midget" bulbs commonly known as fairy lights are also called Italian lights in some parts of the U.S., such as Chicago.
The first known electrically illuminated Christmas tree was the creation of Edward H. Johnson, an associate of inventor Thomas Edison. While he was vice president of the Edison Electric Light Company, a predecessor of today's Con Edison electric utility, he had Christmas tree light bulbs especially made for him. He proudly displayed his Christmas tree, which was hand-wired with 80 red, white and blue electric incandescent light bulbs the size of walnuts, on December 22, 1882 at his home on Fifth Avenue in New York City. Local newspapers ignored the story, seeing it as a publicity stunt. However, it was published by a Detroit newspaper reporter, and Johnson has become widely regarded as the Father of Electric Christmas Tree Lights. By 1900, businesses started stringing up Christmas lights behind their windows. Christmas lights were too expensive for the average person; as such, electric Christmas lights did not become the majority replacement for candles until 1930.
In 1895, U.S. President Grover Cleveland proudly sponsored the first electrically lit Christmas tree in the White House. It was a huge specimen, featuring more than a hundred multicolored lights. The first commercially produced Christmas tree lamps were manufactured in strings of multiples of eight sockets by the General Electric Co. of Harrison, New Jersey. Each socket took a miniature two-candela carbon-filament lamp.
From that point on, electrically illuminated Christmas trees, but only indoors, grew with mounting enthusiasm in the United States and elsewhere. San Diego in 1904 and New York City in 1912 were the first recorded instances of the use of Christmas lights outside. McAdenville North Carolina claims to have been the first in 1956. The Library of Congress credits the town for inventing "the tradition of decorating evergreen trees with Christmas lights dates back to 1956 when the McAdenville Men's Club conceived of the idea of decorating a few trees around the McAdenville Community Center. However, the Rockefeller Center Christmas Tree has had "lights" since 1931, but did not have real electric lights until 1956. Furthermore, Philadelphia's Christmas Light Show and Disney's Christmas Tree also began in 1956. Though General Electric sponsored community lighting competitions during the 1920s, it would take until the mid 1950s for the use of such lights to be adopted by average households.
Over a period of time, strings of Christmas lights found their way into use in places other than Christmas trees. Soon, strings of lights adorned mantles and doorways inside homes, and ran along the rafters, roof lines, and porch railings of homes and businesses. In recent times, many city skyscrapers are decorated with long mostly-vertical strings of a common theme, and are activated simultaneously in Grand Illumination ceremonies.
In the mid 2000s, the video of the home of Carson Williams was widely distributed on the internet as a viral video. It garnered national attention in 2005 from The Today Show on NBC, Inside Edition and the CBS Evening News and was featured in a Miller television commercial. Williams turned his hobby into a commercial venture, and was commissioned to scale up his vision to a scale of 250,000 lights at a Denver shopping center, as well as displays in parks and zoos.
Light-emitting diode (LED) Christmas lights are quickly gaining popularity in many places due to their low energy usage (about one tenth the energy used by incandescent bulbs), very long lifetimes, and associated low maintenance. Colored LEDs are also far more efficient at producing light than their colored incandescent counterparts.
There are two types of LEDs: colored LEDs and white LEDs. Colored LEDs emit a specific color light (monochromatic light), regardless of the color of the transparent plastic lens that encases the LED's chip. The plastic may be colored for cosmetic reasons, but does not substantially affect the color of the light emitted. Because the light is determined by the LED's chip rather than the plastic lens, Christmas lights of this type do not suffer from color fading. In addition, the plastic lens is much more durable than the glass envelope of incandescent bulbs.
White LEDs are similar to colored LEDs in most respects such as power and durability, but utilize a two-stage process to create the white (polychromatic, or broad spectrum) light. In the first stage, the LED actually only produces one color of light, similar to any other LED. In the second stage, some of the blue or violet-blue is absorbed by a phosphor which fluoresces yellow, imitating the broad spectrum of colors which our eyes perceive as "white". This is essentially the same process used in fluorescent lamps, except for the use of an LED to create blue light rather than excited gas plasma to create ultraviolet.
White LEDs can be used as white Christmas lights, or can be used to create any other color through the use of colored refractors and lenses, similar to the more commonly used incandescent bulbs. Color fading may therefore occur due to the exposure of colored plastics to sunlight or heat, as with ordinary Christmas lights. Yellowing may also occur in the epoxy "bulb" in which the LED is encased if left in the sun consistently.
LEDs use much less electricity (only 4 watts for a 70-light string) and have a much greater lifespan than incandescent lamps. Since they are constructed from solid state materials and have no metallic filaments to burn out or break, LEDs are also much less susceptible to breakage from impact or rough handling.
Although LEDs themselves are long-life devices, older or lower-quality strands of LED-based Christmas lights can suffer from early failure. This is particularly so with blue ones, which are the newest and most expensive, and therefore prone to cost-cutting; in addition, spares are rarely included with sets. Most LED-based Christmas lights use copper wire which connects to the aluminum-based wires of the LEDs. Exposing this combination of metals to moisture can result in galvanic corrosion inside of the lamps' sockets, causing them to stop working. Many other sets use cheaper steel leads on the LEDs, which instead rust, leading to the same result. Some newer and higher-quality sets of LED Christmas lights have each LED permanently mounted in a non-removable weathertight base to keep out rain and other moisture, helping to prevent such corrosion; however, this prevents the user from replacing defective bulbs.
Most common consumer LED lamps produce intense, deep, pure colours, versus incandescent bulbs which generally have subtler, yellow-tinted colours, often somewhat faded especially if used outside. Blue tends to be the dimmest incandescent color, but the brightest in LED, while yellow is just the opposite. Very early strings of LED lights were noticeably dimmer than incandescent bulbs, but now are often noticeably brighter. These factors combine to give LED lamps a distinct aesthetic from older incandescent strings, although white LEDs behind coloured lenses do offer the ability to provide a more incandescent-type appearance with most of the benefits of energy efficiency. However, most use coloured-chip type LEDs that produce the intense colours. This is largely due to the maturity of coloured LED versus newer white LED technology, and as the technology improves so will the ability to change the aesthetics of the lamps, at lower cost than at present. As of 2007, "warm white" LED sets are common for the first time in U.S. stores, having a color similar to a compact fluorescent light. However, this color needs to be more of an orange tint to match the color of such small bulbs, because they burn at a lower temperature. Still, this is a significant improvement from the very cold-white (and often irregularly-tinted) color of early white sets.
Additionally, low-end sets do not contain power supplies (or have only a transformer instead of a SELV), and so the bulbs flicker in sync with the alternating current, being completely off when the voltage is negative. This produces a noticeable stroboscopic effect when an individual happens to move the lights across his or her field of view quickly, as when moving the eyes or turning the head rapidly. Higher-quality strings include a bridge rectifier to supply full-wave direct current to the lamps, making the lights brighter and greatly reducing the flickering (though there is still a small amount because diodes need a minimum voltage to begin conducting). Cheaper sets with two circuits connect each in the opposite polarity, which minimizes flicker in the combined light reflected from walls, and also keeps power consumption symmetrical so as not to affect the electrical system.
Many mini sets use standard 3 mm dome-shaped LEDs, and have a plastic cover over them to provide refraction, which is an important step in diffusing the unidirectional light they cast. These covers come in C5, C6, and C7 sizes (⅝, ¾, and ⅞-inch, or 16, 19, and 22 mm diameters, respectively) pointed "strawberries," G12 (12mm or almost ½-inch) globe "raspberries," and "M5" (5mm or -inch) pointed cylinders, equivalent to the T1¾ mini lights so common since the 1980s. For blue and green, these covers may have some fluorescence, leading to a lighter color. Other sets have 5 mm domes with no covers, though because these project light in one direction, many of these instead have a cone-shaped indentation on the top, refracting much of the light out to the sides. Still other sets have covers like snowflakes (or for Halloween, pumpkins). There are also multi-LED screw-in bulbs which replace real C7½ and C9¼ bulbs, and are much closer in brightness than the mini imitations.
Miniature lights sets can come with attached ornaments, typically plastic but sometimes glass. These began mid-century with petal "reflectors" which actually refracted the light and focused it in beams, and perhaps even earlier with crystal-like ones. On both types, the bulb stuck out of the center, and the "reflector" could be removed from the socket. Later designs, though much less popular, included stars. LED lights now come molded into shapes, though the light comes from the top instead of the center.
Mini lights can also have full-size ornaments normally sold on sets of ten. Certain sets have more than one bulb per ornament, such as for snowmen and candy canes which are long. There is an enormous array of other designs, ranging from holly berries and poinsettias to star-shaped santas and wire mesh snowflakes. There are also ones for other holidays.
Christmas lighting began with small C6 bulbs -- C meaning "candle" for the flame shape, and 6 meaning inches (¾ in, or 19 mm) in diameter. These were on a miniature candelabra screw-base, now designated E10 (Edison screw, 10 mm). Replicas of these bulbs are now produced as miniature strings, usually with the entire bulb replaced, but sometimes as a decorative cover with regular bulbs inside. These bulbs tend to be transparent white or colors, and are often ornately designed with crystal-like patterns.
Later bulbs were called C7½, being inches ( in, or 24 mm) in diameter; however, these have a blunt shape (and should therefore be called B7½, or B24). Mixing metric and English units, there are also now G30 globes which are 30 mm ( in, or G9½) in diameter that uses these sockets. These are still used for the classic or even retro look, and use about five watts each. Older bulbs drew 7½ watts of power, and were reduced to save power. Early bulbs, as well as some new antique reproductions, are made in various shapes and then painted like Christmas ornaments. Bubble lights and twinkle bulbs also come in this size.
Outdoor-only bulbs are designated C9¼ ( in, or 29 mm), and have a similar blunt shape as the C7½, but an E17 "intermediate" base. Some modern versions of these strings are now listed for indoor and outdoor use. These bulbs are rated at about seven watts each, and also now come in a globe shape, designated G40 (40 mm, or in). Some of the blunt-shape bulbs now come painted with designs, or swirled in more than one color. It is now very difficult to find twinkle bulbs in this size.
Standard mini bulbs are T1¾, indicating that they are a tube shape inches (5.5 mm) in diameter. Larger mini bulbs, which began appearing around 2004, are about twice this size, but are still very uncommon. Both types, along with most of the candle-shaped ones, are pinched-off at the tip rather than the base during manufacturing. Most contemporary miniature light bulbs have an internal shunt that is intended to activate when the bulb's filament burns out. The shunt closes the circuit across the bad filament, restoring continuity and illuminating the rest of the string. However, if one shunt fails to close properly, the whole string will fail to light. Other miniature types include globe-shaped "pearl" and smaller "button" lights, which are often painted in translucent or pearlescent colors. "Rice" lights are tiny, like a grain of rice, and can even have a subminiature base, if they are not already fixed permanently to the wires (on low-voltage sets). Rice lights are typically transparent, although colored variations do exist. They are intended to create tiny points of light, and are suitable for decorating miniature models, small wreaths, and for other similar situations in which even "midget" T1¾ lights may be too large.
LED lights, which are encased in solid plastic rather than a hollow glass bulb, may be molded into any shape. Because of the way the LED casts light in only one direction, this is the most common way to design LED lighting, with even "plain" sets having some sort of crystal pattern to create refraction.
Many bargain brands have dome-shaped LEDs which focuses the light to where it is sharply visible when viewed head-on, but almost invisible from a perpendicular viewpoint. This has both advantages and disadvantages according to one's decorating needs.
If a small LED bulb size but wider viewing perspective is desired, wide-angle LEDs are available. Rather than being dome-shaped (convex), the envelope is concave (sunken in) to cause wider distribution of light.
All miniature bulbs (including some LED sets) have a wedge base, though the exact design of each is inconsistent, making it somewhat difficult for the average consumer to change bulbs. To replace a bulb, the plastic base of the bulb must usually be changed by straightening the two wires and pulling the glass part out. Most replacement bulbs do not even include the bases anymore, despite getting only ten in a package and being charged nearly half what an entirely new string of 100 costs. For this reason, many Americans treat mini Christmas lights as being disposable, in addition to colored lights tending to fade even with only brief exposure to weathering. Many LED sets are coming permanently wired, with bases that look like conventional pull-out bulbs.
Large C7½ and C9¼ bulbs typically come in sets of 25, though bubble lights come in sets of seven, and some non-holiday sets come in ten or twelve. Sockets are usually spaced about one foot or 30 cm apart, and are clamped to the wire with an integrated insulation-piercing connector. Some older parallel sets had 15 bulbs, as do some of the newer globe sets manufactured today. Both of these bulbs are designed to run on 120 volts and the light sets that use them are parallel wired.
Miniatures first came in sets of 35 (3.5 volts per bulb), and sometimes smaller sets of 20 (6 volts per bulb). Sets of ten (12 volts per bulbs) were made for very small trees, but are quite hot, and are now usually used for tree toppers only. This number is convenient for stars, which have a total of ten points (five outward and five inward), and often have another light in the middle, occasionally on both sides.
Incandescent miniatures now usually come in sets of 50 or 100 (which contains two circuits of 50), though decorative sets with larger bulbs (C6 or pearl style) typically come in 35 or 70. Several "extra-bright" sets also use 70 or 105 bulbs, keeping the per-bulb voltage at 3.5 instead of 2.5.
LED sets can vary greatly. Common is a set of 60 (2 volts per bulb), but white LED sets use two circuits of 30 (4 volts per bulb). Multicolor sets may have special wiring, because red and yellow require less voltage than the newer blue-based ones (blue, emerald green and fluorescent white), but typically come in sets with a multiple of 35.
Battery-powered sets typically come in 10 or 12, and can use standard 2.5 to 3.5-volt bulbs because they run two batteries, totaling three volts or less. LEDs are becoming increasingly common as they greatly prolong battery life, but because they also last longer they are often soldered directly to the wires, making up for some of the increased cost of the newer LEDs. 'Rice lights" are often made this way as well, and likewise may also have more bulbs per set as they draw somewhat less power per bulb than other incandescents.
Controllers can be set up to change flashing or animation styles by pressing a button or turning a dial on the unit; others have only one pattern, but the speed of this pattern can usually be adjusted by turning a similar dial.
Most multi-function sets feature 8 to 16 moving light functions. Some very common functions are fading and chasing. More extravagant and less common functions are stepping on and 2-channel flashing. These lights usually come in sets of 140 or 150. This is because to give the chasing effect, bulbs must be arranged in 4 circuits of 35 (equals 140) or 3 circuits of 50 (equals 150). These light sets use even less power than a regular set of 150 because the lights are not always on, and therefore the bulbs do not get as hot.
Usually, computerized sets cannot be connected end-to-end. However, some newer sets contain special miniature plugs - a "female" plug is located at the end of the set, and a "male" plug is located between the control box and the beginning of the actual lights. By disconnecting the control box from one set, it can now be plugged into the end of an identical chasing set to produce a longer strand of chasing lights. These plugs generally have a twist-on locking feature similar to that found on garden hoses.
Fiber-optic Christmas lighting can also be animated electronically, particularly when the set incorporates LEDs. When an incandescent lamp is used, animation can created by means of a rotating color wheel.
There's a new control technology being developed in Ottawa, Canada Lights On Calico which enables multiple homes to link up over the Internet in-real time and in-synch. A central website initiates the timing using Network Time Protocol to keep the local computers in synch, and each location has a small Java program that controls a device which interfaces with the USB port to which your Christmas lights plug into. In this way, anyone online can "plug in" to this network and at their discretion working independently or in-synch engage their Christmas Light display on a global level.
Incandescent (midget) or LED-based sets usually have each lamp connected in series to be powered without a transformer in the set. Screw-base C7 and C9 light sets use line voltage (120 volt) bulbs and are wired in parallel. LED-based sets use a current-limiting resistor to reduce the current supplied to each LED. Neon-lamp-based sets have lamps connected in parallel, each with its own current-limiting resistor. Battery-powered sets are also wired in parallel.
Some incandescent or LED-based strings use a power supply transformer with lamps connected in parallel. These sets are much safer, but there is a voltage drop at the end of the string causing reduced brightness of the lamps at the end of the set. The reduced brightness is, however, less noticeable with LED-based sets than incandescent sets. Power supplies with integrated plugs may make the set difficult to connect in certain places.
A line-operated AC string with a male plug on one end and a female socket on the other end can be conveniently connected end-to-end with other similar strings. The gauge of wire used and the power consumption of each string will determine how many strings can be safely daisy-chained this way, or whether the end string will have diminished voltage and brightness.
For a series string, fixing failures requires a tedious process: each bulb is replaced with a known good bulb, hunting for the broken one by trial-and-error. If more than one bulb is broken, then each bulb in the broken string needs to be tested in a known-good string. Sometimes a bulb will not actually break, but will come loose in its socket. Its connection can also become corroded. Those two problems can be fixed by resetting each bulb in turn.
In a parallel string, one shorted bulb makes the whole string fail, requiring a similar troubleshooting process. However, the shorted string must be protected by a current limiting device, which may require resetting in between tests.
Fiber optic sets are the simplest to troubleshoot, since they contain only a few light sources, sometimes only one or two, and the place of failure can be located very quickly. Units containing color wheels may also require maintenance of mechanical parts.
The number of strands of continuous light sets that may be safely conjoined varies based on whether the lights are LEDs, ordinary miniature light bulbs, or the larger C7/C9 type light bulbs. Other factors include the voltage of the set and the size of the wiring in the set. Those with questions should consult the manufacturer's instructions or an electrician.
Most light sets come with built in fuses to help protect against overheating and to prevent household fuses or circuit breakers from being tripped. If a fuse blows, the strand must be unplugged and the number of lights must be reduced. If the strand has nothing attached, or has blown repeatedly, it may contain a short circuit and should be discarded.
Hobbyists who don't want to pollute the environment by discarding a damaged set can cut it into many individual bulbs, each of which can be powered by a safe low voltage source. These bulbs can be used in projects such as microcontroller or PC controlled animated displays. The plug of the damaged set should, however, be destroyed and discarded for safety reasons, but this produces much less waste than discarding the whole set.
Some fiber optic sets may use halogen bulbs in their bases, in such cases, all precautions related to this type of bulbs should be observed.
Animated sets should not be watched by people having photosensitive epilepsy. Non-animated sets exist and can be used in such cases.
Many light sets may contain traces of lead in their PVC insulation, and consumers should wash hands thoroughly after handling these products, especially before eating. Proposition 65 of California requires that if products contain lead or traces of lead then a warning must be printed on packing of products. One must be sure to check the label for this and any additional warnings. The purpose of the lead in the PVC insulation is to make the PVC fire retardant, and to protect the PVC from ozone and other airborne pollutants which can crack and degrade the PVC over time.
An episode of the show MythBusters covered the possible fire danger from Christmas lights.
It is often a pastime to drive or walk around neighborhoods in the evening to see the lights displayed on and around other homes. While some homes have no lights, others may have incredibly ornate displays which require weeks to construct. A rare few have even made it to the Extreme Christmas TV specials shown on HGTV, at least one requiring a generator and another requiring separate electrical service to supply the amount of electrical power required.
In 1986, Barry "Mad Dog" Gottlieb, organized the "Tacky Xmas Decoration Contest and Grand Highly Illuminated House Tour" with a tour of decorated homes in Richmond, Virginia. Since then, people either sign up for a tour, or drive around to find houses that are the tackiest. Most of the houses on this tour are completely covered in Christmas lights, similar to the way Clark Griswold decorated his house in the movie Christmas Vacation. The tour has been featured on "NPR", "Great Things About the Holidays on Bravo, "Crazy Christmas Lights" on TLC, and HGTV among other nationally broadcast programs. Locals in Richmond refer to it as the " Tacky Light Tour" and a growing number of cities have adopted this family Christmas tradition.
In Australia and New Zealand, chains of Christmas lights were quickly adopted as an effective way to provide ambient lighting to verandas, where cold beer is often served in the long hot summer evenings. For many years the use of Christmas lights on Australian homes was mainly limited to this simple form. In the last decade increasingly elaborate Christmas lights have been displayed and driving around between 8.00 and 10.00pm to look at the lights has become a popular family entertainment. While in some areas there is fierce competition, with Town Councils offering awards for the best decorated house, in other areas it is seen as a co-operative effort, with residents priding themselves on their street or their neighbourhood.
Halloween is the most popular, with miniature light strings having black-insulated wires and semi-opaque orange bulbs. Later sets had some transparent purple bulbs (a representation of black, similar to blacklight), a few even have transparent green, or a translucent or semi-opaque lime green (possibly representing slime as in Ghostbusters, or creatures like goblins or space aliens). Two types of icicle lights are sold at Halloween: all-orange, and a combination of purple and green known as "slime lights."
Red, white, and blue lights are produced for Independence Day, as well as U.S. flag and other patriotic-themed ornaments. Net lights have been produced with the lights in a U.S. flag pattern. In 2006 some stores carried stakes with LEDs that light fiber-optics, looking similar to fireworks.
These above light strings are occasionally used on Christmas Trees anyway, usually to add extra variety to the colors of the lights on the tree.
Various types of patio lighting with no holiday theme are also made for summertime. These are often clear white lights, but most are ornament sets, such as lanterns made of metal or bamboo, or plastic ornaments in the shape of barbecue condiments, flamingos and palm trees, or even various beers. Some are made of decorative wire or mesh, in abstract shapes such as dragonflies, often with glass "gems" or marbles. Light sculptures are also made in everything from wire-mesh frogs to artificial palm trees outlined in rope lights.