Types of Lamps

Types of Lamps

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Incandescent Lamp

A filament is mounted on a base inside a glass bulb, which can contain gas or be a vacuum. When current is passed through the filament, it is heated until it glows, or incandesces. Eventually, the material of the filament, when heated for long periods of time, starts to evaporate. It gathers on the inside of the bulb (which is why you see blackening of the bulb just before or after burnout). When so much of the filament has eroded that it is no longer stable, it breaks, causing the lamp to burn out.

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Benefits • Has a low initial cost. • Provides excellent color rendering (has a CRI of 90–100). • Comes in a variety of different shapes and sizes. • Turns on instantly. • Requires no ballast. • Is dimmable (dims very well).

Disadvantages • Has a short life (750–2,000 hours). *Note: Keeping a lamp dimmed, even just a small amount, extends its life! • Has very low efficacy, the lowest of all lamp types (about 10–30 lumens/watt). • Is very inefficient (Of all the energy that goes into the lamp, only about 5% is converted to light! The other 95% of the energy is converted to heat, not only making the lamps inefficient, but also giving them a very high temperature.)

Components • Glass Bulb: The glass bulb is typically made of soda lime glass. There are other variations of the glass envelope such as the ones used for Halogen and PAR lamps. They will be discussed below. • Gas: The space in the bulb needs to be a vacuum or filled with gas. Most 40 watt and under lamps are vacuum type. Lamps over 40 watts are commonly filled with a gas mixture of argon and nitrogen. • Filament: The early incandescent lamps Gobel invented had a bamboo filament. Edison used carbon for his. In 1909 Tungsten was used and it is still what is used today. • Base: Incandescent lamps have a variety of bases. They are commonly made from aluminum.

Type of Incandescent: Halogen (or tungsten-halogen)

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Using a halogen gas inside the envelope of the bulb helps create what is known as the halogen cycle. As the tungsten filament starts to evaporate and deposit on the bulb, as it typically does in an incandescent lamp, the halogen gas combines with the tungsten molecules. It is then attracted back to the filament, where the tungsten is redeposited. This greatly increases the lamp’s life and reduces the bulb-wall blackening. This also allows the filament to function at a higher temperature, which produces a higher light output, giving it a higher efficacy than the traditional incandescent lamp.

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Type of Incendescent: PAR Lamps (parabolic aluminized reflector)

Unlike standard household bulbs that emit light in all directions, PAR bulbs feature a built-in reflector and lens. This shape captures the light and focuses it into a concentrated, directional beam—perfect for spotlighting artwork or washing a wall with light.

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The PAR lamp is another type of incandescent lamp and includes a reflector and a lens built into it. These lamps are often used in stage lighting, car headlamps, and residential and commercial recessed lamps.

Type of Incendescent: BR Lamps (bulged reflector)

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Another type of incandescent lamp. Similar to a PAR, but with wider beam angles and a softer coverage. Used in recessed lighting in rooms with high ceilings, stairways, hallways, and places where reduced shadows are desired.

Incandescent Bases and Shapes

Components • Base: The base conducts electricity to the cathode. There are four types of linear fluorescent lamps: single-pin, medium bi-pin, miniature bi-pin, and recessed double contact. • Cathode: This is a coiled wire made of tungsten. There are two of them, one located on each end of the tube. It is coated in a material that gives off electrons when it heats up. • Gases: The inside of the tube is filled with an inert gas, typically argon, kept at very low pressure. • Mercury: There is a small amount of mercury vapor in the tube. Newer lamps are being manufactured with smaller amounts of mercury, which pass the requirements of the Environmental Protection Agency (EPA) for hazardous waste, but the typical, older lamp types are required to be disposed of according to the EPA requirements. • Glass tube: The glass envelope, or bulb, is typically tubular in shape, though it comes in a variety of lengths and diameters and can be bent into a circular or U-shape. • Phosphor coating: This is a white powder coating the inside of the tube. The exact combination of phosphors used determines the color of the light, so manufacturers can create different color temperatures and colors of fluorescent light.

Fluorescent Lamps

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The first fluorescent sources were developed in the 1930s. They quickly became incorporated into commercial design and then residential design. According to the American National Standards Institute/Illuminating Engineering Society of North America (ANSI/IESNA), a fluorescent lamp is "a low-pressure mercury electric-discharge lamp in which a fluorescent coating (phosphor) transforms some of the ultraviolet (UV) energy generated by the discharge into light" (6.5.6.1 Fluorescent lamp).

OperationFluorescent lamps operate differently from incandescent ones. The main similarity is that fluorescent lamps also contain tungsten filaments, but they are now called cathodes. First, an alternating current is passed through a ballast to the cathodes. They function by having electricity conducted to the cathode (also called electrode). The voltage along the cathodes causes electrons to migrate from one end of the lamp to the other. There is a small amount of liquid mercury inside the tube, and this energy causes the mercury to change from a liquid to a gas. The moving electrons at times collide with the mercury gas, which causes them to release UV light as the atoms change energy levels. We are unable to see UV light with our eyes, so we need another step to convert it to visible light. The inside of the tube is coated with a white powder, made of phosphor. When the UV light collides with the phosphor, the phosphor atoms heat up, releasing visible, white light.

Fluorescent lamps also come in a compact form, known as CFLs. They function the same way as linear fluorescent lamps, except that the ballasts are often built in. They are a bit easier to control optically because the light is no longer spread out over a long length. This makes them a viable alternative to incandescent lamps. They come in screw-base type, meaning they are compatible with incandescent luminaires, and with single-ended pin bases.

Benefits• Has high efficacy: 90+ lumens per watt, depending on the ballast, which is much better than the incandescent lamp! • Has a long life: Ten thousand hours for a compact fluorescent and twelve thousand hours for a linear fluorescent. • Provides a variety of whites: By altering the phosphor coating, this lamp can come in a range from warm to mid to cool whites. • Has a low operating cost. • Is a diffuse light source: A lamp can be a "point source" or a "diffuse source." A point source is a lamp whose light is relatively small and compact, which makes it a point of light. Using optics (like reflectors), these lamps are easy to aim and direct into a beam. Diffuse light sources are ones where the same amount of light is spread out in a bigger package. The light coming from them is more spread out, or diffused, and these are harder to aim and use as spotlights/pin lights. Larger lamps create softer shadows, as well.

Fluorescent Lamps

Benefits & Disadvantages

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Disadvantages• Is temperature sensitive: If the temperature is over or under the ideal operating range, the light output is drastically reduced. • Is difficult to control optically: Because it is a diffuse light source, it is difficult to control the light using luminaires and optics. • Requires additional components: Fluorescent lamps need ballasts to operate. Ballast cost, life span, type, and other factors must be considered. *Screw-in CFLs have the ballast already integrated into the lamp design. • May not dim well: If using a magnetic ballast, the fluorescent lamp can typically only be dimmed to about 50%.

Compact Fluorescent Lamps (CFLs)

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Disadvantages• Is temperature sensitive: If the temperature is over or under the ideal operating range, the light output is drastically reduced. • Is difficult to control optically: Because it is a diffuse light source, it is difficult to control the light using luminaires and optics. • Requires additional components: Fluorescent lamps need ballasts to operate. Ballast cost, life span, type, and other factors must be considered. *Screw-in CFLs have the ballast already integrated into the lamp design. • May not dim well: If using a magnetic ballast, the fluorescent lamp can typically only be dimmed to about 50%.

Fluorescent lamps also come in a compact form, known as CFLs. They function the same way as linear fluorescent lamps, except that the ballasts are often built in. They are a bit easier to control optically because the light is no longer spread out over a long length. This makes them a viable alternative to incandescent lamps. They come in screw-base type, meaning they are compatible with incandescent luminaires, and with single-ended pin bases.

Mercury lamps, metal halide, and high-pressure sodium are examples of HID lamps. Due to the color appearance and CRI of mercury and sodium lamps, they are not generally suitable for indoor applications. Therefore, we will be focusing on the metal halide HID lamps.

High Intensity Discharge Lamps (HID)

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OperationHID lamps function very similarly to fluorescent lamps in that they use two electrodes mounted within an inner arc tube, which is placed inside of another outer glass envelope, or bulb. HID lamps produce light through the electric arc discharge that is created when current passes through the electrodes. In a fluorescent lamp, the resulting energy created is UV and needs the phosphor coating to convert it to visible light. In an HID lamp, the material the lamp is filled with determines how the light appears, its efficacy, and its CRI. An HID lamp is named after what it contains (mercury, metal halides, sodium, etc.). In a metal halide lamp, the inner arc tube is filled with metal halides. With these lamps, some UV radiation is produced (like in a fluorescent lamp), so sometimes, they come with phosphor coatings to convert that UV radiation to light (which also increases the efficacy). They produce a white light in the 3,000 K to 6,000 K color temperature range and have a CRI rating of 60 to 95. Often used to light outdoor spaces like football fields and roadways.

Benefits • Has high efficacy: 70 to 125 lumens per watt. • Has a wide range of wattages: The lamp comes in a range of 32 to 1,500 watts. • Has a long life: The life ranges between 3,000 and 20,000 hours. • Is a point source: Like an incandescent lamp, this is considered a point source. Disadvantages • Color shift • Warm up and restrike time: When you initially turn on a metal halide lamp, it will turn on immediately, but it will take two to ten minutes to “warm up” to its full light output. If you turn it off and try to turn it back on immediately, it will not turn back on (or “restrike”) for up to fifteen minutes. That means that if you are using it in an area that cannot have a loss of light, emergency backup lighting would need to be specified. • Other accessories: This lamp needs a ballast to operate. • Orientation: This lamp needs to be operated/mounted in the upright position. When positioned horizontally, or upside down, it experiences a loss of efficacy.

Others: Ceramic Metal Halide and Mercury Vapor

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Ceramic Metal Halide Recent improvements to the metal halide lamp include new shapes given to the arc tubes in order to improve efficacy and CRI and stabilize color. The use of ceramic materials also helps improve the CRI and the lamp color. PAR versions allow them to increasingly be used in display lighting, accent lightings, downlighting, architectural applications, and even residential applications. Mercury Vapor and High-Pressure Sodium These two lamp types produce a very green-blue light (mercury vapor) and a very yellow light (sodium) because of the material in the inner tube. They come in very high efficacy and wattages and are, therefore, extremely bright and have very low CRIs (in the range of 5–20). These three things together make them inappropriate for most indoor applications. They are typically used on roadways, in parking lots, on sports fields, in school gyms, and in high-bay applications.

Others: Electrodeless and Cold-Cathode (Neon)

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Electrodeless Lamps The first type is called an electrodeless lamp. As you can guess, this lamp does not contain an electrode. Instead, it uses a radio-frequency power supply to pass energy through an induction coil, which excites the mercury glass inside the bulb. The lamp contains a phosphor, which fluoresces when it is excited by UV radiation, much like a fluorescent lamp. Because there are no cathodes that could deteriorate, theoretically, these lamps could burn forever, or until either the electronics fail or they are physically broken. They are very expensive and are rated from ten thousand to hundred thousand hours (that’s eleven years!). Cold-Cathode Lamps Cold-cathode lamps, also known as neon lights, work similarly to fluorescent lamps. They produce light by the fluorescence of their phosphor coating. Fluorescent lighting is known as hot-cathode lighting because it contains two filament-like cathodes. Cold-cathode lighting uses a closed-ended metal cylinder, instead. The color is created depending on the gas inside it. Neon produces red light, and argon produces blue light. Different phosphor coatings are then added to the neon or argon to produce a wide variation of colors.

How LEDs are Different LED lighting is very different from other lighting types such as incandescent and CFL. Key differences include: Light Source: LEDs are the size of a fleck of pepper, and can emit light in a range of colors. A mix of red, green, and blue LEDs is sometimes used to make white light. Direction: LEDs emit light in a specific direction, reducing the need for reflectors and diffusers that can trap light. This feature makes LEDs more efficient for many uses such as recessed downlights and task lighting. With other types of lighting, the light must be reflected to the desired direction and more than half of the light may never leave the fixture. Heat: LEDs emit very little heat. In comparison, incandescent bulbs release 90% of their energy as heat and CFLs release about 80% of their energy as heat. Lifetime: LED lighting products typically last much longer than other lighting types. A good quality LED bulb can last 3 to 5 times longer than a CFL and 30 times longer than an incandescent bulb. Can now be used for residential and commercial lighting including homes, parking garages, offices, institutional, industrial, and commercial spaces. ----U.S. Dept of Energy

Light Emitting Diode (LED) Lamps

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LED An LED is one of the most talked-about lamp types seen today. LEDs are very small and produce light by the process of electroluminescence (a p-n junction diode, which produces light when activated). They were originally limited to red and seen in remote controls and small electronic lights. Today, they come in red, green, blue, and white, which means they can be combined to create every color in the visible spectrum. They have a long life and a high efficacy. "LED is a highly energy-efficient lighting technology, and has the potential to fundamentally change the future of lighting in the United States. Residential LEDs -- especially ENERGY STAR rated products -- use at least 75% less energy, and last up to 25 times longer, than incandescent lighting." ----U.S. Dept of Energy

Benefits of LEDs: Extreme Energy Efficiency, Extreme flexibility in dimming and color control, Extremely long life

The many types and shapes of LEDs available today

Nearly all types, styles and shapes of lamps can now be produced with LED technology

According to the U.S. Dept. of Energy, over 70% of all lamps in use in the U.S. today are LEDs (and that is projected to rise to 87% by 2030

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