LED Lighting Attributes and Terminology
Application -- There are many different kinds of LED bulbs made for different purposes including use in businesses, homes, medical facilities, electronics, and wherever there is a need for light. For example, LED tubes can be used to replace fluorescent lights, while standard bulb shaped LEDs can be used in lamps and other common lighting fixtures including chandeliers and floodlights. They can also be used in illuminating signs, replacing neon lights. LED bulbs are not recommended for use in high-heat appliances such as microwave ovens and range hoods, though they are excellent for use in colder appliances like refrigerators.
"A" light bulbs: standard household use bulbs
"B" and "C" light bulbs: with their bulged base and either rounded or pointed tapered end, these bulbs resemble a flickering flame and are used in chandeliers and night lights; smaller ones are used in most holiday strand lights or electric candles.
"PAR" light bulbs: Parabolic Aluminized Reflector lamps, used for spotlights and accent lighting, have a reflective cover that focuses the light. LED versions of the PAR bulbs do not need their covers to be reflective because LEDs offer a more focused light spread on their own.
See also: Bulb Shape
Ballast -- An electrical ballast limits the amount of current pulled in by an electric circuit. Without a ballast, fluorescent lighting systems would uncontrollably increase their draw of electrical current at a rapid rate from the power source.
Ballast Compatible: some LED replacements for fluorescent lights are compatible with the ballasts and some are not. Bulbs that are not ballast compatible require the LED replacement to be re-wired and retrofit into the existing lighting fixture.
Plug & Play: These linear lamp LEDs (shaped like a fluorescent light tube) snap into place, as easily as replacing a regular light bulb. They cost more but don't require the ballast to be removed for the new LED to be wired into the power source.
Base -- The part where the bulb attaches to the fixture.
See also: Fitting
Beam Angle -- This is the angle at which light is distributed from the bulb. LEDs come in a wide variety of beam angles. The exact measurements for vary slightly from one manufacturer to the next, but in general these are the degrees for each type of flood:
Omni-directional: These bulbs have at least a 300 degree beam angle.
Wide flood: A beam angle between 90 degrees and omni-directional will give a wide flood.
Medium flood: A 45-90 degree beam angle will give a medium flood.
Narrow flood: 25-45 degrees is a medium-narrow flood, and 25 degrees or less is a narrower flood, good for a spot light.
Bulb Shape -- Light bulbs have designated shape and measurement codes. These codes are expressed in a letter-number-letter format. The first letter describes the shape of the bulb, the number conveys the diameter at its widest point, and the optional final letter can be used to indicate the length.
In the U.S., the diameter is measured in 8ths of an inch, so an A20 bulb means it’s a standard, household bulb shape that's 20/8 inches in diameter, or 2.5 inches. In other countries, the number conveys the measurement in millimeters.
Color -- RGB Color Changing LEDs can illuminate with different colors. Most models have the option to select a specific color and change it manually, or to allow the light to cycle through multiple colors. RGB stands for red, green, and blue, and those three colors in the LED can mix to also create yellow, turquoise, violet, and white.
Color Temperature -- Color temperature is measured in Kelvin (K), which indicates the hue of the light and is not a measurement of heat. The higher the value, the closer the hue of the light is to actual sunlight. The lower the value, the more yellow-tinted the light is. Color temperatures 5,000K and above are a bright bluish white, and lower color temperatures (2,700-3,000K) are warmer yellow-ish light. Very low Kelvin values will have a redder hue.
See also: CRI
CRI -- Stands for Color Rendering Index, which measures how accurately a light source makes the color of an object appear to its true color. The CRI runs on a scale of 0-100, and the higher the Index number, the better the light source is at rendering color. Light sources with a CRI of 85-90 are good, while 90 and above is excellent. CRI is dependent on color temperature as the hue of the light cast can affect perception of the object's color. A 2700K warm color temperature has a CRI of 100. Brighter, "sunlight" color temperatures closer to 5000K have CRI's of 75-90.
See also: Color Temperature
Dimmable -- Dimmer switches specifically for LEDs do exist, but many LEDs are made to be compatible with existing household dimmer switches.
Leading-edge: These dimmers are used to dim traditional incandescent and halogen light bulbs. They have a higher wattage range (usually between 250-1,000W) meaning the LEDs that don't meet the required tolerances aren't going to work with these dimmer switches, though some LED bulbs are made to be compatible.
Trailing-edge: These dimmers have a much lower wattage range and were made specifically to work with LED bulbs.
DLC -- DesignLights Consortium is a project of the Northeast Energy Efficiency Partnerships (NEEP), a North American regional non-profit founded in 1996. DLC collaborates with stakeholders in the lighting industry to define high performance through technical requirements and facilitate thought leadership. DLC also works to provide resources and expertise to its members and the industry.
DLC Qualified -- the DLC Qualified Products List (QPL) is a list, available to the public, of high quality and high efficiency LED products for consumers. DLC qualifies products like commercial LEDs, retrofit kits, and linear replacement lamps to be included in DLC member programs for incentives and energy efficiency rebates. Products must meet technical and category-specific requirements to be eligible for qualification on the DesignLights QPL.
ENERGY STAR -- ENERGY STAR is a program with the U.S. Environmental Protection Agency (EPA) that helps businesses and individuals save money and protect the environment with superior energy efficiency. The ENERGY STAR certification mark can be used to label products, homes, and buildings that have been verified as meeting ENERGY STAR's requirements for energy efficiency. Homes and business partnering with ENERGY STAR save energy by using efficient products and practices.
ETL Listed -- The Electrical Testing Labs were founded by Thomas Edison in 1896 to provide assurance to consumers that the approved electrical products were safe to use. Products with the ETL Listed Mark have been independently tested and meet the lab's standards, which are published. Intertek's ETL listing of products are compliant with North American safety standards. These products have been tested by a Nationally Recognized Testing Laboratory (NRTL) which are independent laboratories recognized by the Occupational Safety and Health Administration (OSHA). These labs test electronic products to determine if they meet the safety specifications applicable to the product.
FCC Listed -- The Federal Communications Commission (FCC) was established in 1934 by the Communications Act and reports to Congress. The FCC is in charge of regulating interstate and international communications via radio, television, wire, satellite, and cable. Any such device that operates at a clock rate of 9 kHz is required to be tested and meet the applicable FCC codes.
Fitting -- Also called the base, the fitting is the part where the bulb attaches to the fixture.
Candelabra E12: A small screw-in base with a diameter of 12mm. Candelabra bases can also be found in 11mm (mini) and 14mm (European). -Medium E26: Standard screw-in 26mm diameter base. This is the most standard base size for light bulbs in the U.S., it is used in most lamps and light fixtures around the home.
Intermediate E17: Medium size screw in base with a diameter of 17mm. Light bulbs with this size base are usually found in commercial EXIT signs, ceiling fans, and some appliances.
Mogul E39 and E40: These are much larger bases, sometimes made of ceramic, generally used in commercial lighting appliances. Will need a lamp base adaptor when replacing these with medium-base LED bulbs.
GU24: This is a 2-pin twist-&-lock connector base. The number measures the distance between the two pins in millimeters.
Example of a 2-pin connector base:
Flashable -- These LEDs are usually used in business signs to be more attention-grabbing. Flashing LEDs have a multivibrator circuit that makes the light flash, usually with a period of one second per flash. Most emit one color, but some are made to flash a multi-color sequence using RGB color mixes.
Halogen Bulbs -- Halogen is the name for a family of electronegative elements. These elements include bromine, chlorine, fluorine, and iodine. Halogen bulbs originally contained iodine, but now are commonly made with bromine. These light bulbs are a type of incandescent lighting that uses a halogen gas to increase light output. Both halogen and incandescent bulbs work by heating a tungsten filament until it's hot enough to emit light, but halogen bulbs have a higher brightness when compared to incandescent light bulbs. Blackening of the bulb's glass is prevented by the halogen gas as it chemically reacts with the tungsten evaporating from the filament. The glass of incandescent bulbs blackens because the gas mixture inside is commonly nitrogen and argon, which deposit the tungsten onto the glass rather than back in the filament.
IP Rated -- IP stands for ingress protection, and it's expressed as a two-digit number that indicates the effectiveness of sealing on the enclosures of electrical equipment, protecting it from dust and moisture.
The first digit indicates, on a scale of 0 to 6, how well protected the enclosure is against contact with moving parts.
0 = no special protection
1 = protection for any larger surface of the body, such as the back of the hand, but no protection against deliberate contact with a body part
2 = Protection against fingers and similar objects
3 = Protection from entry by tools, thick wires, and similar objects
4 = Protection from entry by solid objects with a thickness greater than 1mm, which includes most wires and screws
5 = Protection from the amount of dust that would interfere with the operation of the equipment
6 = Dust tight.
The second digit indicates how protected the enclosure against moisture.
0 = no special protection
1 = Protection from vertically dripping water for a duration of not more than 10 minutes; water equivalent to 1mm of rainfall per minute
2 = Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15 degrees from its normal position for not more than 10 minutes; water equivalent to 3mm rainfall per minute
3 = Water falling as a spray at any angle up to 60 degrees for not more than 5 minutes shall have no harmful effect; water volume up to 0.7 liters per minute; water pressure up to 80-100 kN/m²
4 = Protection from splashed water from any direction for not more than 5 minutes; water volume up to 10 liters per minute; water pressure up to 80-100 kN/m²
5 = Protection from water projected from a nozzle (6.3mm) against the enclosure from any direction for not more than 3 minutes shall have no harmful effects; water volume up to 12.5 liters per minute; water pressure up to 30 kN/m² from a distance of 3 meters
6 = Protection against heavy seas or water projected in powerful jets (12.5mm nozzle) against the enclosure from any direction for not more than 3 minutes shall have no harmful effects; water volume up to 100 liters per minute; water pressure 100 kN/m² at a distance of 3 meters
7 = Ingress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (up to 1 meter of submersion for no more than 30 minutes)
8 = The equipment is suitable for continuous immersion in water under conditions specified by the manufacturer. Normally this will mean that the equipment is hermetically sealed, however, with certain types of equipment, it can mean that water can enter but only in such a manner that it produces no harmful effects.
Instant-on -- Requires no warm-up time, when you turn the light on it is at its fullest lumen output and brightest color instantly.
LED -- Stands for light-emitting diode. LEDs are semiconductor devices, which emit visible light when an electric current passes through it. Most LEDs are monochromatic and occur at a single wavelength.
LED Features -- Some LEDs are available with features such as dimmer switch compatibility, ballast compatibility, shatterproof glass, and flashable capabilities.
See also: Ballast, Dimmable, Flashable, and Shatterproof
Life Hours -- The average lifetime of the bulb before it burns out. Bulbs are typically available in 15,000; 25,000; 50,000; or 100,000 life hours.
Lifetime Savings -- The average amount of money saved in a bulb's lifetime by using LEDs, compared to the use of traditional light bulbs. The LED bulb costs more initially but it won't burn out as quickly and it uses less energy and electricity, saving money in the long run.
Lifetime savings chart from energystar.gov
Light Spread -- The area of the object illuminated by the light source. A greater beam angle provides a larger light spread, and a lesser beam angle provides a smaller light spread
See also: Beam Angle
Lumens -- The unit used to measure brightness levels emitted from a light source. Lumen levels emitted per watt varies slightly, but in general, to replace a 100 watt incandescent bulb, you need an LED bulb that gives you about 1600 lumens (usually 18W).
Initial lumens: Also known as the initial light output, initial lumens are the total amount of lumens produced by a specific lighting device immediately after it has stabilized but before depreciation starts.
Mean lumens: The lumen output from conventional lighting devices tends to decrease in amount the longer the lamp is on, so the mean is the average lumen output from when its initial lumens depreciate to when the light is turned off.
Lumens per Watt (LPW) --LEDs emit more lumens while using less wattage. The exact conversion varies slightly from one manufacturer to another, but generally a 4 watt LED bulb will give you the same brightness level as a 25 watt incandescent bulb, and an 18 watt LED light produces the same brightness level as a 100 watt incandescent bulb.
Part Number -- Number codes used to identify a product.
MPN: Manufacturer Part Number is given to the part by the manufacturer to identify the product.
UPC: Universal Product Code is a barcode uniquely assigned to trade items to identify the product. This is mainly used to scan an item at checkout.
Retrofit LEDs -- Retrofitting lights is to replace the existing ones with new light technology. This is usually done to increase energy-efficiency. For example, replacing fluorescent or metal halide lighting with an LED system. Many companies offer LED bulbs that can be placed in existing light fixtures, as easily as changing the lightbulb, but some require retrofit kits that contain supplies and instructions to install the wiring.
RoHS Compliant -- Restriction of Use of Hazardous Substances regulates the limits or total ban of specific substances, e.g. lead, cadmium, mercury, in new electronic or electric-powered equipment and products. These regulations were designed to limit or eliminate substances that are harmful to the environment and to people. The aforementioned substances and others regulated by RoHS create pollution, as well expose manufacturer and recycling employees to multiple health dangers. Companies can send their products to laboratories that offer RoHS testing to determine if their products comply. Before sending them to a lab for final testing, companies can also use handheld devices called XRF analyzers that can detect the presence of substances limited or banned by RoHS. The RoHS originated in the European Union in July of 2006, and all applicable products on the EU market after that date must pass the test for compliance. Banned substances include lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (CrVI), polybrominated biphenyls (PBB), polybrominated diphenyl ether (PBDE), and four different phthalates (DEHP, BBP, BBP, DIBP).
Shatterproof -- LED light bulbs with shatterproof glass are a safer bulb and great for use in a variety of places, especially stores, hotels, restaurants, medical facilities, and homes.
Size -- Measured in inches in the U.S., basic bulb dimensions are given in length and width at the overall longest and widest points.
Temperature Notes -- LED bulbs do not generate heat like incandescent or halogen bulbs. They work better in colder (even in sub-zero) temperatures than other lamps do, but they do lose efficiency and lumen-output when used in high heat environments for prolonged periods of time.
Operating temp: the cooler the ambient temperature of the room/area, the longer and brighter the LEDs will illuminate. Standard room temperature or below is ideal.
Traditional Equivalent -- The approximate incandescent/fluorescent/halogen/metal halide equivalent wattage needed to produce the same amount of lumens as an LED is as follows:
Incandescent: 40W needs to be replaced by a 6W LED
Fluorescent: 32W needs to be replaced by a 15W LED
CFL (Compact Fluorescent Light): 9W needs to be replaced by a 6W LED
Halogen: 42W needs to be replaced by a 10W LED
Metal Halide: 70W needs to be replaced by a 35W LED
Tube Length -- The length of the tube of an LED replacement for conventional fluorescent lights: 2ft., 3ft., 4ft., and 8ft. lengths
UL Listed -- A product carrying UL Listing Mark meets the Underwriters Laboratories safety requirements. The UL Mark is commonly seen on computers, furnaces and heaters, fuses, smoke detectors, carbon monoxide detectors, and electrical panelboards, among many other types of products. UL listing and testing for products can be verified with the UL online directories at www.ul.com.
Voltage -- For replacing standard light bulbs, voltage is not an issue. Being concerned about voltage comes into play when someone is building their own LEDs and LED devices with small LED pin bulbs.
Warranty -- Standard warranty terms, may vary from one manufacturer to the next: If it does not last for the [2, 3, or 5 years of the warranty] when used as directed return with proof of purchase, registered receipt, and your name and address to [the manufacturer] and receive a replacement or equivalent option.
Wattage -- Watts are used to measure the amount of energy a light bulb is using. The higher the wattage, the more energy used (and the higher the electric bill). LEDs have lower wattage than incandescent bulbs, but have a higher lumens per watt output.