LED Christmas lights are small, colored, light emitting diodes that are linked together by a wire and used to decorate trees, window frames, the roofline of houses, and other items as a way to celebrate the holiday season. Unlike traditional miniature incandescent bulbs, they are illuminated by the movement of electrons in a semi-conductor material rather than heat causing an internal filament to glow. LED lights are very efficient, so they don't produce much heat or waste electricity.
The bulbs in LED Christmas lights are typically available in many different shapes, from the traditional cylinders with pointed tips, to balls and cubes, to special designs that look like pine cones or snowflakes. They also produce deep, pure colors rather than the typical yellow-tinted light from traditional incandescent bulbs. LEDs can be made to mimic the "warm" yellow tones of those lights, however, or the sharper, blue-based "cool" colors.
Most Christmas lights come linked together with several strands of wire, which can be green, white, or another color. In many cases, the wire will have a plug on each end — one that can be inserted into an electrical outlet, and one connector that accepts a plug from another strand so that they can be linked together. Rope lights are also available, which have the lights and wires inside of a plastic tube.
Lights are available with one- or two-piece construction, although the two-piece is more commonly available in stores. In one-piece sets, the individual lights are not removable. Because the entire bulb assembly is sealed together, it's less likely that moisture will get into the strand, damaging it; it also prevents loose connections from turning the lights dark. Individual lights cannot be replaced if they burn out.
A string of LED Christmas lights uses about 1/10th of the electrical current of mini incandescent lights. This means that not only are they less expensive to use, more strands can be connected together without overloading the circuit. LEDs are also much cooler than traditional lights because they don't need the heat to glow. Holiday lights are linked to about 150 home fires each year, and although not all are linked to the heat generated by such lights, LEDs are thought to be safer.
Most LED lights are made from plastic instead of glass, so they are less likely to break. The color is also generated in the diode itself, rather than in the bulb, although the bulbs are often tinted to the same as the light; if the external plastic fades, it won't change the color produced. The bulbs last longer because there is no internal filament to burn out.
Despite their reputation for being long-lasting, LED Christmas lights can and do burn out or become less bright. In most cases, as long as a bulb is still attached to the strand, the rest of the lights will continue to work, however. Lights made with two-piece construction can also have a problem with loose bulbs; if the connection between the bulb and the socket is not tight, part or all of the strand may fail. It can be very difficult to find the loose bulb when this happens.
Unlike incandescent bulbs, LEDs can glow or flicker when switched off. Most electrical devices receive a constant trickle of electricity when plugged into a power source, which can sometimes be enough to make the lights turn on a little even when set to off.
LED lights can also be more expensive than traditional incandescents. Although the price is likely to drop over time, it can be difficult for a consumer to justify the upfront expense of new lights, especially if older sets still work. This higher price is usually offset by the electricity savings over time, as well as their longer life.
Caring for LED Christmas lights is usually very simple. The string of lights can simply be rolled up and stored after the holiday is over. Because the bulbs are durable, the strand will usually work during the next holiday season. In addition, the relative thickness of the wires used for these lights make them less likely to get tangled in storage.
LEDs have been around since the 1960s, but didn't become popular as Christmas lights until the beginning of the 21st century. Older types originally came in only red, which prevented them from becoming very popular. Encasing a red LED in colored glass does not produce a light the same color as the glass; rather, it is a mixture of the two colors, severely limiting the color options. As the technology improved, however, a wider range of colors and shapes became available.