I’ve been reading the “Summary of Results: Round 9 of Product Testing,”(warning – this link opens a PDF file) by the US Department of Energy’s Solid-State Lighting CALiPER Program. If you are interested in the current state of LED lighting products, it makes for some fascinating reading. One big concern I have had both testing and installing LED tube lights from various manufacturers as well as looking at lots of product information from a wide range of vendors, is that there is definitely huge variation in quality, and it is clear that some products don’t live up to the vendor descriptions.

The Department of Energy (DOE) created the CALiPER program to attempt to help address some of the quality and consistency issues that purchasers of LED lighting continue to encounter. CALiPER is an acronym for the Commercially Available LED Product Evaluation and Reporting Program. The program was established in 2006 to investigate the performance of luminaires and replacement lamps that use LEDs. To help users better compare LED products with conventional lighting technologies, CALiPER also has performed benchmark research and testing of traditional (i.e., non-LED) lamps and fixtures.

The DOE has performed tests of a wide range of LED lighting products, and overall they have found that with each successive generation of testing, performance has improved significantly. One of the key areas they looked at in round 9 was what they describe as use of solid state lighting (or LED lighting) technology to replace fluorescent troffers. “Troffer” is a term used to describe a recessed luminaire that is installed in the plenum with the opening flush with the ceiling. Typically rectangular or square in shape, as in a 2-foot-by-4-foot luminaire. Fluorescent and LED tube lights are often installed in troffers. The CALiPER Round 9 testing tested examples from two different approaches to using LED technology to replace fluorescent troffers. In products that are designed to replace 2’x2’ troffers, LED products tested were integral luminaires, meaning that they are complete fixtures rather than replacement lamps for existing troffers. In products designed to be used in 2’x 4’ troffers, LED lighting products tested were linear replacement lamps (LED tube lights), marketed to replace the 4’ T8 or T12 fluorescent tube lamps in existing troffers.

Example of Integral 2' by 2' LED Lighting Panel

Some of these LED tube lights that were tested are designed to function using the same ballast as fluorescent lamps, so their installation does not require removing the ballast from the troffer. However, this testing found that lamps designed to use the fluorescent ballast have lower overall efficacy than those designed to use their own drivers (in CALiPER testing, losses were 10-20% higher for LED lamps using the fluorescent ballast). Most of the LED tube lights require that the ballast in existing troffers be bypassed (as discussed in detail in an earlier post on installing LED tube lights), using their own driver; an approach which enables somewhat more efficacious designs.

In a nutshell. what the CALiPER testing found was that the LED tube lights did not yet match the fluorescent lights they are marketed to replace. What’s more, the CALiPER researchers found that the majority of manufacturers of LED tube lights that they tested provide incorrect data—some promising as much as 50% more lumens than their products deliver. Similarly the lumens per Watt documented by the manufacturers ran between 30 and 50% higher than the products measured. CRIs in general were also lower—most promised 80 or higher, when in fact, a few had CRIs in the mid-70s and half were in the mid-60s.

The CALiPER testers did find that several of the 2′x2′ LED panels that they tested met or exceeded the performance levels of the fluorescent lights they were designed to replace.

So, does this mean that we should give up on fluorescent tube lights?  I don’t think so.  Performance continues to improve, and the best of the products tested are beginning to approach the performance levels of equivalent fluorescent tubes. As the CALiPER report notes, fluorescent troffers can be among the most efficacious lighting applications available today. By using high-performance lamps, high-performance troffer designs, and judicious choices in ballasts, these fixtures can provide extremely economical and efficient lighting. Therefore, this is one of the most challenging lighting application areas for LED when it comes to providing similar levels of energy efficiency. Given the targeted high efficacies and light outputs required by troffer applications, optimal LED product design will be needed to be competitive. The best products available today provide great solutions when used in the right applications. The reduced energy consumption and extremely long performance life of even these products can overcome other limitations.

Isn't It About Time to Upgrade the Tube Light Fixture?

In a recent post, I described how to retrofit a fluorescent lighting fixture to support LED tube lights, and in another post I explained in detail why this is necessary. Now, since LED tube lights have been on the market for at least three years now, one might expect that at least one fluorescent lighting fixture manufacturer would have introduced a fixture specifically designed for installation of the new LED tube lights. After all, the product is really a lot simpler, since the most complex and costly element in most of these fixtures, the ballast, is no longer required.

Some vendors have taken steps to deal with this issue.  One approach is to eliminate the need to retrofit the fixture at all.  Some vendors are introducing tube lights that are designed to work without having to remove the ballast, such as the EverLED-TR from a Virginia-based company called EverLED, but this particular product is priced at least twice the cost of most comparable LED tube lights on the market. I have come across a few examples of what appear to be retrofits of standard fixtures either bundled with LED tubes or marketed as a solution for LED tube lights, but these appear to be one-offs or made-to-order as opposed to an actual purpose-built fixture.

The unique attributes of LED lighting will ultimately lead to the replacement of tube light fixtures with LED lighting panels, but that will likely be a long time in the future.  In the near term, the standardized form factors and familiarity that so many have with fluorescent tube fixtures and bulbs would see to suggest a market opportunity for purpose-built fixtures designed specifically for use with LED tube lights.

Fluorescent Tubes

Introduced in 1938, the fluorescent bulb was the first major lighting advance to achieve widespread commercial adoption following the 1905 introduction of the tungsten incandescent bulb.  Fluorescent bulbs represented a huge increase in efficiency and operating life over incandescent lamps, enabling cooler, brightly lit offices, factories, and schools, as well as home kitchens and baths. This article describes how tube lights work and explains some basic things you should know about fluorescent lighting.

Today, you can find two common types of tube lights:  fluorescent tubes and LED tube lights.  Until recently, the term “tube light” was synonymous with fluorescent light.  LED tube lights have begun to gain traction as a replacement for fluorescent lamps due to their ability to reduce electricity consumption, eliminate the requirement for toxic mercury, and significantly longer operating lives; however, the vast majority of tube lights are still the familiar fluorescent bulbs.  Some purists object to calling these lights “fluorescent tubes,” preferring to call them “fluorescent bulbs” or “fluorescent lamps,” but with the introduction of LED tube lights designed to replace the fluorescent bulbs in these fixtures, the use of the term “tube light” is becoming more common.

Fluorescent lamps are a type of gas discharge tube similar to neon signs and mercury or sodium vapor street or yard lights.  The basic concept behind a fluorescent lamp is that a flow of electrical current occurs between two metal conductors placed in a glass tube, a process also known as arcing.  The pair of metal connectors (electrodes) is sealed along with a drop of mercury in a gaseous phase and some inert gases (usually argon) at very low pressure inside the glass tube.  The inside of the tube is coated with a phosphor which produces visible light when excited with ultraviolet (UV) radiation.  The electrodes are in the form of filaments which for preheat and rapid or warm start fixtures are heated during the starting process to decrease the voltage requirements and remain hot during normal operation as a result of the gas discharge (bombardment by positive ions).

Fluorescent Tube Components

When the lamp is off, the mercury/gas mixture is non-conductive.  When power is first applied, a high voltage (several hundred volts) is needed to initiate the discharge.  However, once this takes place, a much lower voltage -usually under 100 volts for tubes under 30 watts, 100 to 175 volts for 30 watts or more – is needed to maintain it.

The electric current passing through the low pressure gases emits quite a bit of UV (but not much visible light).  The internal phosphor coating efficiently converts most of the UV to visible light.  The mix of the phosphor(s) is used to tailor the light spectrum to the intended application.  Thus, there are cool white, warm white, colored, and black light fluorescent (long wave UV) lamps.  There are also lamps intended for medical or industrial uses with a special envelope such as quartz that passes short wave UV radiation.

Fluorescent lamps are from 2 to 4 times more efficient than incandescent lamps at producing light at the wavelengths that are useful to humans.  As a result, they operate at a cooler for the same effective light output.  In addition, the bulbs themselves last a lot longer (10,000 to 20,000 hours versus 1,000 hours for a typical incandescent bulb).  However, for certain types of ballasts, this is only achieved if the fluorescent lamp is left on for long periods of time without frequent on-off cycles.

A fluorescent tube is incorporated into a fluorescent lighting system which may be a separate fixture or self-contained within a bulb as in the case of compact fluorescent (CFL) bulbs.  A fluorescent lighting system consists of two or three main components: (1) the fluorescent lamp (fluorescent bulb), (2) the ballast, and (3) the starter system. In addition, the system for a tube lamp includes a lamp holder and a switch.  Depending on the particular fluorescent lighting system, the starter may be a replaceable component, a starter may not be required, or the starter function may be integrated into the ballast. The starting function may also rely on the physical design of the fixture. To retrofit a fluorescent light fixture to support an LED tube light, the ballast (and the starter if a separate one is present) must be disconnected.

Let’s take a closer look at each of these components.  Turning first to the lamp holder, the most common is designed for the straight bi-pin base bulb.   The 12-, 15-, 24-, and 48-inch straight fixtures are common in household and office use.  The 4-foot (48″) type is the most widely used size.   Ballasts are available for either 1 or 2 lamps.  Fixtures with   4 lamps usually have two ballasts.  The modern electronic ballast performs two functions: current limiting and providing the starting kick to ionize the gas in the fluorescent tubes.  Older fixtures may have a starter.  The starter is a device to initiate the electrode preheating and high voltage “kick” needed for starting.  Again, in most fixtures in use today, the ballast handles this function.  Finally, the switch provides on/off control unless connected directly to building wiring in   which case there will be a switch or relay elsewhere.  The power switch   may have a momentary “start” position if there is no starter and the ballast does not provide this function.

Fluorescent Tube Sizing (T12 on the left and T8 on the right)

An LED tube light is radically different in design and operation from a traditional fluorescent lamp.  The LED tube light consists of four essential components: the LED circuit board, a heat sink and power supply, and a shell. The LED tube light contains no gas and does not require a ballast or starter. The LEDs themselves are semiconductors, and LED lights are often described as solid state lighting.

Example of LED Replacement Tube Showing LEDs

Fluorescent tubes are identified by several letters and numbers and will look something like “F40CW-T12” or “FC12-T10.”

The typical labeling you will see is of the form FSWWCCC-TDD (although, variations on this format are not uncommon):

Example Fluorescent Tube Label (F14T12/CW)

Despite all of their advantages over incandescent lights, fluorescent lights due create some safety and environmental concerns.   Fluorescent and compact fluorescent lamps (CFLs), high intensity discharge lamps (HID) lamps contain a small amount of mercury and are identified with the elemental symbol Hg.  With the growing adoption of CFLs, there has been increasing awareness of the need to safely dispose of these bulbs.  In fact, ten states and multiple local jurisdictions prohibit the disposal of mercury containing products, including CFLs and other mercury containing lamps, in solid waste.  However, CFLs average less than 4 milligrams of mercury.  This is about the amount that would cover the tip of a ballpoint pen. By comparison, older thermometers contain about 500 milligrams of mercury, an amount equal to the mercury in 125 or more CFLs.  Still, given the shear volume of these bulbs that are thrown away each year, they result in a lot of mercury pollution.  The statistics are actually pretty staggering.  As of 2008, seventy-one percent of mercury-containing lamps used by businesses and 98 percent used in homes still were not being recycled. Each year, the lighting industry uses approximately 9 tons (8.2 metric tons) of mercury in manufacturing fluorescent lamps.  Of the 514 million lamps per year that enter the solid waste stream, about 142 million come from private homes and 372 million come from businesses, the government, and institutions. You can help eliminate this problem by looking for recycling options. Web sites such as Earth 911 and Light Recycle can provide local disposal options.

A more immediate danger is posed by the phosphor-coated glass on a broken fluorescent bulb.  If cut with fluorescent lamp glass, phosphor that gets into the wound can prevent blood clotting and will interfere with healing. Such injuries should be treated seriously and immediate medical attention should be obtained for people or pets that are cut. Medical personnel should be informed that the injuries were caused by a broken fluorescent lamp, and that mercury was present.

Ballasts can also overheat and fail.  Because a failing ballast can grow extremely hot, it can become a fire hazard. Modern ballast designs have an internal temperature sensor that shuts the ballast off it gets too hot. In most designs, when the ballast cools off, the sensor will allow the ballast to turn back on. A fixture where some or all of the lamps shut off by themselves and later come back on is probably a fixture with a failing ballast.

Finally, some research suggests that fluorescent lighting may trigger headaches, migraines and other physical symptoms. Research in England revealed that 100Hz fluorescent lighting creates an imperceptible flicker that can cause visual discomfort and make it more difficult to read accurately. Long-term clinical studies by the Irlen Institute have concluded that fluorescent lighting in schools may be related to many academic and health problems. A 2006 study by Capital E found that students in schools with natural light instead of fluorescent lighting had a 10 percent to 21 percent higher learning rate and higher test scores. A document prepared by the Irlen Institute reports that fluorescent lighting may trigger headaches, migraines and other physical symptoms.

The new LED tube lights appear to eliminate all of these safety and environmental issues, and we can expect to see them gradually replace fluorescent tube lights.

How much electricity can you expect to save by installing LED tube lights?  Well, it depends, of course, on what kind of fluorescent bulbs you are replacing, whether there was an electronic or magnetic ballast and the rated wattage of the replacement bulb or bulbs, but you are guaranteed to use less electricity than is required by an equivalent fluorescent tube.

Here’s a simple demonstration someone put together using a handy Kill-a-Watt home power meter.

OK, This Is a Little Over the Top...

Compact Fluorescent Lights (CFLs) along with more traditional fluorescent lamps are now being aggressively marketed as environmentally friendly due to their reduced electricity consumption. Indeed, widespread replacement of incandescent bulbs with CFLs will greatly reduce electricity demand; however, there are safety issues that ultimately contribute to making LED lighting the superior choice. Understanding fluorescent lighting risks can help ensure that fluorescent light bulbs are used and disposed of safely while explaining why LED lighting is the safest and most eco-friendly lighting choice in the long run.

Mercury

The most commonly cited fluorescent lighting hazard is mercury. Fluorescent and CFL bulbs contain a small amount of mercury and are identified with the elemental symbol Hg. When these bulbs are cold, some of the mercury in the lamp is in liquid form, but while the lamp is operating or when the lamp is hot, most of the mercury is in a gaseous or vapor form.

Example of Mercury Label on CFLs and Fluorescents

Mercury vapor is extremely toxic. Even in liquid form, contact with mercury is considered life-threatening or a “severe” risk to health. Even very small doses of mercury can cause severe respiratory tract damage, brain damage, kidney damage, central nervous system damage, and many other serious medical conditions.

CFLs average less than 4 milligrams of mercury, about the amount that would cover the tip of a ballpoint pen. By comparison, older thermometers contain about 500 milligrams, an amount equal to the mercury in 125 or more CFLs. Although the amount of mercury in each fluorescent lamp is small, it is always important to avoid breaking fluorescent lamps, and used bulbs must be delivered to a hazardous waste handler. Never place fluorescent lamps in trash compactors or incinerators, since this will release the mercury and contaminate the surrounding area.

Disposed of improperly, mercury can contaminate buildings, landfills, lakes, animals, fish, birds, humans, crops and rivers. In the US, the EPA has ordered waste handlers to treat fluorescent lamps as hazardous waste. With such a classification, fluorescent lamps are not to be sent to landfills, but instead are to be sent to recycling centers that break the lamps under special conditions and safely recover the mercury. Up to 95 percent of the mercury contained in CFLs can be recovered if the bulbs are recycled properly.

Mercury-containing lamps generated by households and small businesses are not always subject to legal restrictions regarding their disposal. State laws vary and some states, such as California, Maine, New Hampshire, Minnesota, Vermont and Massachusetts, prohibit all mercury-containing lamps, including CFLs, from being discarded in the solid waste stream. In addition, many local ordinances require recycling of mercury-containing products, including lighting. It is best to check with your municipality to understand whether there are local requirements addressing mercury-containing waste disposal.

Because mercury will be released if a fluorescent lamp is broken, it is important to install fixtures in areas where the lamps are not likely to be broken. Fixtures in areas close to the ground or in areas with moving equipment should use metal or plastic shields to protect the lamp from being broken. If a fluorescent lamp breaks, there are numerous safety and cleanup issues which we discuss in more detail in the following section.

Breakage

Fluorescent lamps create several hazards if broken. Depending on the type, there may be a partial vacuum or the lamp may be under pressure. Breaking the glass can cause shrapnel injuries, along with the release of mercury and other hazardous compounds.

Broken Fluorescent Tube

The biggest immediate injury threat from a broken lamp is from the phosphor-coated glass. If cut with fluorescent lamp glass, any phosphor that gets into the wound is likely to prevent blood clotting and will interfere with healing. Such injuries should be treated seriously and immediate medical attention should be obtained for people or pets that are cut. Medical personnel should be informed that the injuries were caused by a broken fluorescent lamp, and that mercury was present.

To minimize exposure to mercury vapor, EPA and other experts advise a few precautions. Children and pets should stay away from the area, and windows should be opened for at least 15 minutes so that vapors may disperse. Cleanup can be done by hand using disposable materials. Use rubber disposable gloves and scoop up the materials with stiff paper or cardboard. Use sticky tape to pick up small pieces and powder, clean the area with a damp paper towel, and dispose of the materials in an outside trash can. Never use a vacuum because this will only disperse the mercury vapor and leave particles trapped inside the cleaner bag.

CFL Disposal Tips

Dimmers

Never use a CFL with a dimmer in the circuit (unless it is specifically made to work with dimmers), even if the dimmer is set at the maximum setting. Doing so places you at risk of fire and at the very least will dramatically shorten the life of the lamp and the dimmer. Also most photocells, motion sensors and electric timers are not designed to work with a CFL. Check with the manufacturer for the use of a CFL for these types of fixtures.

Notice the Warning about Use with Dimmers

To use a CFL on a dimmer switch, you must buy a bulb that’s specifically made to work with dimmers (check the package). GE makes a dimming compact fluorescent light bulb (called the Energy Smart Dimming Spirals®) that is specially designed for use with dimming switches. I don’t recommend using regular compact fluorescent bulbs with dimming switches, since this can shorten bulb life. Using a regular compact fluorescent bulb with a dimmer will also nullify the bulb’s warranty.

Finally, if a CFL bulb “buzzing” when it is installed in a fixture that is controlled by a dimmer switch, this is an indication that you have the wrong type of CFL bulb installed.

Electrical

Any fluorescent fixture that uses lamps longer than 24″ or that is used outdoors or in a damp, wet, or high-humidity location must have an electrical ground for the fixture and ballast. All rapid-start and instant-start fluorescent fixtures must have an electrical ground in order to operate properly. Fixtures with longer lamps operate at higher voltages, with some fixtures having starting voltages across the lamp as high as 950 VAC. Voltages at this level represent a strong shock hazard and improperly grounded fixtures or direct contact with electrical connectors or other wiring can result in severe injury or death.

When servicing fluorescent fixtures and lamps, electrical power to the entire fixture should be disconnected. This is not always practical in situations where a large number of fixtures are controlled from the same power control (such as in open office areas). In these cases, insulating gloves and a nonmetallic ladder should be used if the fixtures must be serviced when power is present. This advice also applies when retrofitting a fluorescent fixture to mount LED tube lights.

Overheated Ballasts

Fluorescent lamp ballasts can fail. Leaving burned-out lamps in the fixture, using the wrong size lamps, incorrect wiring, incorrect line voltage, operation at temperatures below or above the rated limits, power surges, and even the age can all cause a ballast to fail. However, not all ballasts fail and stop functioning. Many overheat. Because a failing ballast can become extremely hot, it can become a fire hazard. Modern magnetic ballast designs have internal temperature sensors that shuts the ballast off it gets too hot. In most designs, when the ballast cools off, the sensor will allow the ballast to turn back on. A fixture where some or all of the lamps shut off by themselves and later come back on is probably a fixture with a failing ballast. Any ballast can overheat due to incorrect wiring, a component failure, or a power surge. Electronic ballasts are supposed to all shut off when they fail, but some types of failure may prevent that shutdown.

PCBs

Prior to the 1970s, some ballasts, particularly those used to control “High-Output” lamps, contained PCBs. PCBs are carcinogens, and their use in electrical equipment has been banned since the 1970s, but a ballast made before this date could contain this compound. In these older ballast designs, the PCB compounds could leak out of a ballast if it is overheated or if the ballast case is physically damaged. If a ballast is leaking a clear or light colored oil, it may indicate the presence of PCBs. If the model number and manufacturers name are still on the ballast, contact them and ask if the ballast contained PCBs.

Short-Wave Ultraviolet Light

A long-term hazard from fluorescent lighting is the shorter-wave ultraviolet (UV) light that escapes the lamp. No matter how well crafted, some short-wave ultraviolet light escapes from every fluorescent lamp made. Short-wave UV light is one of the damaging components of the suns rays that reach the surface of the Earth, which can directly damage organic tissue and trigger cancers. Short-wave UV light can also age or damage paper, fabrics and other materials.

Generally, fixtures with a plastic lens leak the smallest amount of UV light, mainly because most of the ultraviolet light gets absorbed in the plastic lens. Fluorescent lighting in museums, archival libraries and manufacturing “clean room” areas usually have UV-absorbing sheeting applied to the lamps or the fixture lens to eliminate all UV light. LED bulbs do not produce any UV light.

Flicker and Glare

Flicker and glare from fluorescent lights can also cause headaches and have been found to impact learning and ability to concentrate. Although humans cannot see fluorescent lights flicker, the sensory system in some individuals can somehow detect the flicker. Ever since fluorescent lighting was introduced in workplaces, there have been complaints about headaches, eye strain and general eye discomfort. These complaints have been associated with the light flicker from fluorescent lights. When compared to regular fluorescent lights with magnetic ballasts, the use of high frequency electronic ballasts fluorescent lights resulted in more than a 50% drop in complaints of eye strain and headaches. There tended to be fewer complaints of headaches among workers on higher floors compared to those closer to ground level; that is, workers exposed to more natural light experienced fewer health effects.

Long-term clinical studies that conclude fluorescent lighting in schools may be related to many academic and health problems. A 2006 study found that students in schools with natural light instead of fluorescent lighting had a 10% to 21% higher learning rate and higher test scores. Fluorescent lighting may trigger headaches, migraines and other physical symptoms. Many children have been mislabeled with learning disabilities, ADD/ADHD, reading problems and dyslexia all because of students having to work under fluorescent lights. With cool-white fluorescent lighting, some students demonstrated hyperactivity, fatigue, irritability, and attention deficits.

Lamps operating on alternating current (AC) electric systems produce light flickering at a frequency of 120 Hertz (Hz, cycles per second), twice the power line frequency of 60 Hz (50 Hz in many countries outside North America). Essentially, the power is turning on and off 120 times a second (actually the voltage varies from +120 volts to -120 volts, 60 times or cycles a second and is at zero volts twice in one cycle). People cannot notice the flicker in fluorescent lights that have a flicker rate of 120 cycles per second (or 120 Hz).

Flicker is usually a potential problem only with lighting that require the use of ballasts, like fluorescent lights. Incandescent lights usually do not cause a flicker problem since the light filaments generally do not cool quickly enough (and make the light dimmer) during the “off” time as the voltage changes in the AC power line. New, energy-efficient electronic ballasts take the 60 Hz power and convert it to voltages at a much higher frequency. The resulting flicker frequency is so high that the human eye cannot detect any fluctuation in the light intensity – essentially flicker-free. An added benefit is that electronic ballasts produce less hum than that emitted by other kinds of ballasts.

Manufacturers and regulators have taken steps to eliminate this problem with LED lights. In the US, the new Energy Star criteria for integrated LED replacement lamps include a requirement for 150 Hz operation (now being challenged by manufacturers who cite studies that 120 Hz is sufficient). The majority of low-frequency AC LED systems already operate in the rectified mode, which effectively doubles the luminous modulation frequency to 120Hz for 60Hz mains in the US. Despite many attempts, laboratory investigations have not found statistically significant evidence of luminous modulation with frequencies over 100Hz on human performance, health, or comfort.

Evolution of the Light Bulb: From Edison to LED

One-hundred-and-thirty years ago, Thomas Edison completed the first successful sustained test of the incandescent light bulb. With some incremental improvements along the way, Edison’s basic technology has lit the world ever since. This is about to change. We are on the cusp of a semiconductor-based lighting revolution that will ultimately replace Edison’s bulbs with a far more energy-efficient lighting solution. Solid state LED lighting will eventually replace almost all of the hundreds of billions of incandescent and fluorescent lights in use around the world today. In fact, as a step along this path, President Obama last June unveiled new, stricter lighting standards that will support the phasing out of incandescent bulbs (which already are banned in parts of Europe).

To understand just how revolutionary LED light bulbs are as well as why they are still expensive, it is instructive to look at how they are manufactured and to compare this to the manufacture of incandescent light bulbs. This post explores how incandescent light bulbs are made and then contrasts that process with a description of the typical manufacturing process for LED light bulbs.

So, let’s begin by taking a look at how traditional incandescent light bulbs are manufactured. You will find that this is a classic example of an automated industrial process refined in over a century of experience.

While individual incandescent light bulb types differ in size and wattage (determining the amount of light the bulb gives off in lumens), all incandescent bulbs have the three basic parts: the filament, the bulb and the base. The filament is made of tungsten. While very fragile, tungsten filaments can withstand temperatures of 4,500 degrees Fahrenheit (2,480 degrees Celsius) and above. The use of the tungsten filaments is considered one of the greatest advancement in light bulb technology because these filaments can be produced cheaply and last longer than materials used in earlier bulbs.

Incandescent Bulb Components

1. Outline of Glass bulb
2. Low pressure inert gas (argon, neon, nitrogen)
3. Tungsten filament
4. Contact wire (goes out of stem)
5. Contact wire (goes into stem)
6. Support wires
7. Stem (glass mount)
8. Contact wire (goes out of stem)
9. Cap (sleeve)
10. Insulation
11. Electrical contact

The connecting or lead-in wires are typically made of nickel-iron wire. This wire is dipped into a borax solution to make the wire more adherent to glass. The bulb itself is made of glass and contains a mixture of gases, usually argon and nitrogen, which increase the life of the filament. Air is pumped out of the bulb and replaced with the gases. A standardized base holds the entire assembly in place. The base is known as the “Edison screw base.” Aluminum is used on the outside and glass is used to insulate the inside of the base.

Originally made by hand, light bulb manufacturing is now almost entirely automated. First, the filament is manufactured using a process known as drawing, in which tungsten is mixed with a binder material and pulled through a die (a shaped orifice) into a fine wire. Next, the wire is wound around a metal bar called a mandrel in order to mold it into its proper coiled shape, and then it is heated in a process known as annealing which softens the wire and makes its structure more uniform. The mandrel is then dissolved in acid.

Second, the coiled filament is attached to the lead-in wires. The lead-in wires have hooks at their ends which are either pressed over the end of the filament or, in larger bulbs, spot-welded.

Third, the glass bulbs or casings are produced using a ribbon machine. After heating in a furnace, a continuous ribbon of glass moves along a conveyor belt. Precisely aligned air nozzles blow the glass through holes in the conveyor belt into molds, creating the casings. A ribbon machine moving at top speed can produce more than 50,000 bulbs per hour. After the casings are blown, they are cooled and then cut off of the ribbon machine. Next, the inside of the bulb is coated with silica to remove the glare caused by a glowing, uncovered filament. The label and bulb wattage are then stamped onto the outside top of each casing.

Fourth, the base of the bulb is also constructed using molds. It is made with indentations in the shape of a screw so that it can easily fit into the socket of a light fixture.

Fifth, once the filament, base, and bulb are made, they are fitted together by machines. First, the filament is mounted to the stem assembly, with its ends clamped to the two lead-in wires. Next, the air inside the bulb is evacuated, and the casing is filled with an argon and nitrogen mixture. These gases ensure a longer-life for the filament. The tungsten will eventually evaporate and break. As it evaporates, it leaves a dark deposit on the bulb known as bulb-wall blackening.

Finally, the base and the bulb are sealed. The base slides onto the end of the glass bulb such that no other material is needed to keep them together. Instead, their conforming shapes allow the two pieces to be held together snugly, with the lead-in wires touching the aluminum base to ensure proper electrical contact. After testing, bulbs are placed in their packages and shipped to consumers.

Light bulbs are tested for both lamp life and strength. In order to provide quick results, selected bulbs are screwed into life test racks and lit at levels far exceeding their normal. This provides an accurate measure of how long the bulb will last under normal conditions. Testing is performed at all manufacturing plants as well as at some independent testing facilities. The average life of the typical household bulb is 750 to 1,000 hours, depending on wattage (contrasted to 35,000 to 50,000 hours for many LED bulbs).

LED light bulbs are built around solid-state semiconductor devices, so the manufacturing process most closely resembles that used to make electronic products such as personal computer motherboards.

Three Views of LED Replacement Bulb With Edison Screw

LED is, if course, an acronym for Light Emitting Diode, a solid state electrical circuit that generates light by the movement of electrons in a semiconductor material. LED technology has been around since the late 1960s, but for the first 40 years LEDs were primarily used in electronics devices to replace miniature light bulbs. Within the last decade, advances in the technology finally boosted light output high enough for LEDs to begin to seriously compete with incandescent and fluorescent light bulbs. As with many technologies, as the cost of production falls each successive LED generation also improves in light quality, output per watt, and heat management.

The computer industry is well suited to manufacture LED lighting. The process isn’t a whole lot different than making a computer motherboard. The companies making the LEDs themselves are generally not in the lighting business, or it is a minor part of their business. They tend to be semiconductor houses that are happy cranking out their product, which is why prices on high-output LEDs has fallen so much in the last 15 years.

LED bulbs themselves are expensive in part because it takes a number of LEDs to get wide-area illumination instead of a narrow beam, and the assembly cost adds to the overall price. In addition, assemblies consisting of arrays of LEDs create more opportunities for product defects.

An LED light consists of four essential components: an LED circuit board, a heatsink, a power supply, and a shell. The lights start out as bare printed circuit boards (PCB) and high luminance LED elements arrive from separate factories which specialize in making those components. LED elements themselves create a bit of heat, so the PCB used in lighting fixtures is special. Instead of the standard non-conductive sandwich of epoxy and fiberglass, the circuit board is laid out on a thin sheet of aluminum which acts as a heatsink.

The aluminum PCB used in LED lighting is coated with a non-conducting material and conductive copper trace lines to form the circuit board. Solder paste is then applied in the right places and then Surface Mount Technology (SMT) machines place the tiny LED elements, driver ICs, and other components onto the board at ultra high speeds.

The round shape of a traditional light bulb means that most LED printed circuit boards are circular, so for ease of handling several of the smaller circular PCBs are combined into one larger rectangular PCB that automated SMT machinery can handle. Think of it like a cupcake tray moving from one machine to the next along a conveyor belt, then at the end the individual cupcakes are snapped free from the tray.

Let’s take a look at the manufacturing steps for a typical LED light bulb meant to replace a standard incandescent bulb with an Edison Screw. You will see that it is a very different process from the highly automated processes used to manufacture our familiar incandescent bulbs. And, despite what you might imagine, people are still very much a necessary part of manufacturing process, and not just for testing and Quality Assurance either.

Once the larger sheets of LED circuit boards have passed through a solder reflow oven (a hot air furnace that melts the solder paste), they are broken up into the individual small circuit boards and power wires manually soldered on.

The small power supply housed in the body of the light bulb goes through a similar process, or may be delivered complete from another factory. In either case, the manufacturing steps are the same; first the PCB passes through SMT lines, then it goes to a manual dual in-line package (DIP) assembly line where a long row of factory workers add one component at a time. DIP refers to the two parallel rows of leads projecting from the sides of the package. DIP components include all integrated chips and chip sockets.

While LED lights burn several times longer than incandescent or CFLs and require less than half the energy, they need some form of passive heatsink keep the high-power LEDs from overheating. The LED circuit board, which is made from 1.6-2mm thick aluminum, will conduct the heat from the dozen or so LED elements to the metal heatsink frame and thus keep temperatures in check. Aluminum-backed PCBs are sometimes called “metal core printed circuit boards,” and though made of a conductive material the white coating is electrically isolating. The aluminum PCB is screwed in place within the heatsink which forms the lower half of the LED light bulb.

After this, the power connector board is fixed in place with adhesive. The small power supply converts 120/240V AC mains power to a lower voltage (12V or 24V), it fits in the cavity behind the aluminum PCB.

Shell assembly consists of locking the shell in place with screws. A plastic shell covers the power supply and connects with the metal heatsink and LED circuit board. Ventilation holes are included to allow hot air to escape. Wiring assembly for plug socket requires soldering wires to the bulb socket. Then shell is attached.

Next, the completed LED light is sent to burn-in testing and quality control. The burn-in test typically lasts for 30 minutes. The completed LED light bulb is then powered up to see if it is working properly and burned in for 30 minutes. There is also a high-voltage leakage and breakdown test and power consumption and power factor test. Samples from the production run are tested for high-voltage leaks, power consumption, and power factor (efficiency).

The finished bulbs pass through one final crimping step as the metal socket base is crimped in place, are bar-coded and identified with lot numbers. External safety labels are applied and the bulb is inked with information, such as brand and model number. Finally, comes the LED light cover assembly which is glued in place.

After a final check to make sure all the different parts of the LED light are tight, then it is packed into individual boxes, and bulbs are shipped out.

So, if you have wondered why LED light bulbs are so expensive today, this explanation of how they are manufactured and how that compares to the manufacture of traditional light bulbs should help. However, it also reveals why the cost will fall pretty dramatically over the next few years. Just as the cost of manufacturing other semiconductor-based products has fallen dramatically due to standardization, automation and other key steps along the manufacturing learning curve, the same inexorable forces will drive down the costs of LED light bulb production.

Top and Side Views of T8 LED Tube Lights vs. T8 Fluorescent Bulb

1. While the initial cost per bulb is still high, the total lifetime cost of an LED light bulb is actually much lower than that of equivalent incandescent and CFL bulbs. Taking into consideration energy costs as well as time and resources required to replace shorter-lived incandescent and CFL bulbs, an LED bulb that lasts 80,000 hours has a much lower lifetime cost.

2. LEDs are diverse, and many types are useless for general lighting applications.  The finest LED chips emit light with a Color Rendering Index of 85%. LED light bulbs that use top-quality LEDs will last much longer than the novelty bulbs that many are selling and 60% longer than many competing bulbs that use inferior LEDs.

3. LEDs do generate heat, and this heat is the biggest problem that manufacturers face developing LED lighting applications. Manufacturers can now produce individual LED chips that are as bright as a 100-watt incandescent bulb, but these LEDs are practically useless for general lighting because installing them in a fixture creates ventilation problems that have not yet been solved. LEDs installed in fixtures and bulbs must be ventilated properly, and the better the chip, the more difficult it is to properly cool. There are many LED light bulbs on the market that do not take this into consideration and either use cheap chips so they don’t have to ventilate them, or do not ventilate their chips properly, significantly reducing its lifespan. While the typical LED light bulb is barely warm to the touch, if the chip is not properly ventilated, it can fail prematurely.

LED Tube Light Front and Back (Displaying Heatsink on Back)

4. The life-span of an LED light bulb should be its “half-life.”  LED light bulbs do not burn out; rather, they gradually fade out.  When a vendor says an LED bulb will last 80,000 hours, they mean that at that point, the chips will have reached 50% efficiency, and the bulb ought to be replaced. So, the bulb might last 100,000 hours or more, but its efficiency will have degraded greatly by that point.  Using this 100,000-hour life as a selling point is therefore misleading. While LEDs don’t last forever, they will last 50-75 times longer than a comparable incandescent and 6-8 times longer than a CFL.

5. Searching the web, you will quickly find that the LED light bulb market is inundated with product. Many of these bulbs are relatively inexpensive (less than $20); however, you may find that many of these LED bulbs consist of questionable materials and dubious craftsmanship. Good LED light bulbs cost more than these cheap ones because they use high-quality chips with prices firmly set by reputable manufacturers like Cree. This means that though these LED light bulbs are more expensive, they are far superior.

6. Dimming an LED light bulb is tricky. LEDs require constant current to operate. Because of this, if a standard dimming method is applied, it will flicker at regular intervals, or worse, simply not work. In order to dim an LED light, a 0-10V dimming module is required in order to “trick” the LED into emitting less light. In theory, all LED lights are dimmable with this module.

7. When comparing LED light bulbs, you need to understand lumens.  The lumen is a standard unit you can use to compare LED light bulbs to standard bulbs, such as incandescents and halogens. Roughly, a lumen is a measure of brightness. Lumen quantity is important, but maybe more important is lumen quality, i.e., luminous efficacy (lumen/Watt). Today’s quality LEDs have a luminous efficacy between 60-70 lumens/watt.

8. Color temperature and beam spread are the other key tools for comparing LED lights.  Both color temperature and beam spread are measured in degrees. Color temperature refers to the color of the light emitted. In general, 3000 Kelvin is warm white (closer to infrared light) and 5000 Kelvin is cool white (closer to ultraviolet light). Cool white is brighter because it is the natural color of LED light, whereas chips that emit a warm white light require a phosphorous “filter” to “warm” the color temperature, thus reducing the chip’s brightness. Beam spread is the angle of the light that is being emitted. The lower the number, the more like a “spot” the light is.

So, the first question many of you may have is what are LED lights are and what makes them special?

LED stands for light-emitting diode.  LEDs are actually semiconductors (just like computer chips) that emit energy in the form of light when electricity is passed through them. They are doped or injected with certain chemicals that determine their light color. LEDs convert the majority of energy passed through them to light, as opposed to incandescent bulbs that produce light as a by-product of being heated.  For this reason, LEDs  are as much as 90 percent more efficient than traditional household filament light bulbs.

Components of an LED

LEDs have been widely used in as displays and indicator lights for nearly 40 years.  Only recently, though, have engineers figured out how to make and mass-produce bright, white LEDs that can be used for general-purpose lighting.  The high brightness and point-source characteristics of LEDs have made them the first choice for traffic lights and car tail lights, where visibility and dependability are essential.

While the brightness of LEDs made them a good alternative to HID (High Intensity Discharge), CFL (Compact Fluorescent) and incandescent bulbs for certain applications, until recently, they lacked the lumen output and optical control required for general illumination.  However, advances in LED efficiency have changed that, making LED light bulbs the best choice for environmentally-friendly, cost-effective lighting.  Furthermore, just as other semiconductor technology has continued to improve in efficiency even as costs have plummeted, LED technology will continue to increase in efficiency as costs fall, guaranteeing that LED lights will become the dominant for of lighting in the future.