The Definitive guide: LED Linear Lighting

This new guide will show you everything you need to know about LEDs and LED linear lighting

First, I’ll show you what is LEDs and LED lighting

Then, I’ll help you to get the right LED linear lighting for your application or business.

Sound good? Let’s dive right in

discover what is LED lighting


  • <id=”chapter1″>Chapter 1: What is LED and how it works?
  • Chapter 2: LEDs history and the inventor
  • Chapter 3: LEDs types
  • Chapter 4: Where LEDs being used for?
  • Chapter 5: LED lighting associations and Standards
  • Chapter 6: The types of LED linear lighting
  • Chapter 6: The benefits and disadvantages of LEDs lighting
  • Chapter 7: The LED noun explanation and questions

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What is LED?

LED is an acronym for Light Emitting Diode. The LED is a light source which uses semiconductors and electroluminescence to create light. There are two major kinds of light emitting diodes: LED and OLED. The LED is different than EL lamp in that it uses a small semiconductor crystal with reflectors and other parts to make the light brighter and focused into a single point.

A light-emitting diode (LED) is a semiconductor device that emits visible light when an electric current passes through it. The light is not particularly bright, but in most LEDs it is monochromatic, occurring at a single wavelength. The output from an LED can range from red (at a wavelength of approximately 700 nanometers) to blue-violet (about 400 nanometers). Some LEDs emit infrared (IR) energy (830 nanometers or longer); such a device is known as an infrared-emitting diode (IRED).

Where are the LEDs being used?

Early LEDs were often used as indicator lamps, replacing small incandescent bulbs, and in seven-segment displays. Recent developments have produced high-output white light LEDs suitable for room and outdoor area lighting. LEDs have led to new displays and sensors, while their high switching rates are useful in advanced communications technology.

How LED works?

The LED is a specialized form of PN junction that uses a compound junction. The semiconductor material used for the junction must be a compound semiconductor. The commonly used semiconductor materials including silicon and germanium are simple elements and junction made from these materials do not emit light. Instead compound semiconductors including gallium arsenide, gallium phosphide and indium phosphide are compound semiconductors and junctions made from these materials do emit light.

These compound semiconductors are classified by the valence bands their constituents occupy. For gallium arsenide, gallium has a valency of three and arsenic a valency of five and this is what is termed a group III-V semiconductor and there are a number of other semiconductors that fit this category. It is also possible to have semiconductors that are formed from group III-V materials.

The light emitting diode emits light when it is forward biased. When a voltage is applied across the junction to make it forward biased, current flows as in the case of any PN junction. Holes from the p-type region and electrons from the n-type region enter the junction and recombine like a normal diode to enable the current to flow. When this occurs energy is released, some of which is in the form of light photons.

It is found that the majority of the light is produced from the area of the junction nearer to the P-type region. As a result the design of the diodes is made such that this area is kept as close to the surface of the device as possible to ensure that the minimum amount of light is absorbed in the structure.

To produce light which can be seen the junction must be optimised and the correct materials must be chosen. Pure gallium arsenide releases energy in the infra read portion of the spectrum. To bring the light emission into the visible red end of the spectrum aluminium is added to the semiconductor to give aluminium gallium arsenide (AlGaAs). Phosphorus can also be added to give red light. For other colours other materials are used. For example gallium phoshide gives green light and aluminium indium gallium phosphide is used for yellow and orange light. Most LEDs are based on gallium semiconductors.

How a light emitting diode works
How LED works

Chapter 2: LEDs history and the inventor

The LED history

The early years of the 1960s consisted of a ‘race’ in the field of semiconductors. Gallium arsenide and germanium were some of the first semiconductors uses before silicon became the preferred material in the industry. Engineers were experimenting with p/n junctions. These devices were being developed as diodes since they can pass current in one direction by not the other. GE, Bell Labs,Lincoln Labs, RCA research labs, and Texas Instruments worked to develop semiconductors for power control and laser technology.

It was in this race that the LED was ‘discovered’ in the Fall of 1961 by James R. Biard and Gary Pittman. Gary had been working in the related field of solar cells since 1958. In their efforts to try to make an X-band GaAs varactor diode they created tunnel diodes (which had been developed first at Esaki). They placed the tunnel diode on a GaAs substrate and discovered that there must be light production going on during forward bias operation. Using an infrared detector just brought in from Japan they tested it and discovered that the devices lit up brightly!

Soon after this others made discoveries in the field, however TI was the first to get a patent and sell the first LED for $130 each. The SNX-100 was the first LED sold (summer of 1962). The LEDs were first used with IBM computers to replace tungsten bulbs that controlled punch card readers (infrared light was sent through the holes, or blocked by the card). Today there is a myriad of applications for the LED.

The First LED

Above: this experiment of a tunnel diode atop a GaAs semi-insulating substrate convinced Pittman and Biard that there must be light emission going on, and resulted in further experimentation.

Who is H,J Round?

H.J. Round

1907 – H.J. Round discovered electroluminescence when using silicon carbide and a cats whisker. Oleg Losev independently discovered the phenomena the same year.
London, United Kingdom

who is Oleg V. Losev?

Oleg V. Losev

1920s – Oleg V. Losev studied the phenomena of light emitting diodes in radio sets. His first work on ‘LEDs’ involved a report on light emission from SiC. In 1927 he published a detailed report but his work was not well known until the 1950s when his papers resurfaced.
Saint Petersburg, Russia

who is James R. Biard?

James R. Biard

1961 – James R. Biard. “Bob” Biard and Gary Pittman developed the Infrared LED at Texas instruments. This was the first modern LED. It was discovered by ‘accident’ while TI tried to make an X-band GaAs varactor diode. The discovery was made during a test of a tunnel diode using a zinc diffused area of a GaAs (Gallium Arsenide) semi-insulating substrate.
Dallas, Texas

who is gary pittman

Gary Pittman

1961 – Gary Pittman worked together with James R. Biard. He had started working in 1958 with semiconductor GaAs for the creation of early solar cells. He discovered and developed the infrared LED with James R. Biard.
Dallas, Texas

who is Nick Holonyack

Nick Holonyack Jr.

1962 – Nick Holonyack Jr. develops the red LED, the first LED of visible light. He used GaAsP (Gallium Arsenide Phosphide) on a GaAs substrate. General Electric.
Syracuse, New York

who is Geroge Craford?

M. George Craford

1972 – M. George Craford creates the first yellow LED at Monsanto using GaAsP. He also develops a brighter red LED.
St. Louis, Missouri

Herbert Maruska and Jacques Pankove

Herbert Maruska and Jacques Pankove

1972 – Herbert Maruska and Jacques Pankove develop the violet LED using Mg-doped GaN films. The violet LED is the foundation for the true blue LED developed later.
RCA Labs , New Jersey

who is Shuji Nakamura

Shuji Nakamura

1979 – Shuji Nakamura develops the world’s first bright blue LED using GaN (Gallium nitride). It wouldn’t be until the 1990s that the blue LED would become low cost for commercial production.
Tokushima, Japan

who is Thomas P. Pearsall

Thomas P. Pearsall

1976 – Thomas P. Pearsall develops special high brightness LEDs for fiber optic use. This improves communications technology worldwide. Paris, France

Chapter 3: LEDs types

Types of LEDs?

Through-hole LEDs

These are available in different shapes and sizes and the most common ones being 3mm, 5mm and 8mm LEDs. These LEDs are available in different colors like Red, Blue, Yellow, Green, White, etc.

what is through-hole LEDs

SMD LEDs (Surface Mount Light Emitting Diodes)

Surface Mount or SMD LEDs are a special packages that can be easily surface mount on a PCB. SMD LEDs are usually differentiated based on their physical dimensions. For example, the most common SMD LEDs are 3528 and 5050.  It also called Chip On Board (COB).

what is SMD LEDs?

Advantage of SMD led over led with pins:

  • Compact in size

  • Square or rectangular in shape

  • Short leads

  • More efficient

  • More luminous flux in small dimensions.

  • Customizable output power

RGB LED (Red – Blue – Green LED)

RGB LEDs are the most favorite and most popular LEDs among hobbyists and designers. Even computer builds are very popular for implementing RGB LEDs in Computer Cases, Motherboards, RAMs, etc.

RGB LED contains 3 LEDs on a single chip and by a technique called PWM (Pulse Width Modulation), we can control the output of the RGB LED to produce a wide range of color

what is RGB LEDs

High – Power LEDs

An LED with power rating greater than or equal to 1 Watt is called a High Power LED. This is because, normal LEDs have a power dissipation of few mill watts.

High – Power LEDs are very bright and are often used in Flashlights, Automobile Headlamps, Spotlights, etc.

Since the power dissipation of High – power LEDs is high, proper cooling and usage of heat sinks is required. Also, the input power requirement for these LEDs will be usually very high.

what is Hi-power LEDs?

Bi-color LEDs

The next type of LEDs are Bi-color LEDs, as the name suggests, can emit two colors. Bi-color LEDs have three leads, usually two anodes and a common cathode. Depending on the configuration of the leads, the color will be activated

Top global LED chip manufacturers


Manufactured in the USA, CREE is one of the leading LED chip brands in the world with SMD LED chips ranging from 0.1W up to 5W and COB from 5W up to 200W. CREE manufacture LEDs for almost all kind of luminaries either it is a Bulb or a 1000W flood light. CREE high power LEDs are extremely efficient, with a luminous efficacy up to 200 Lm/W.Best thing using CREE LEDs is their technical support and tools available on their website. For example, CREE Product Characterization Tool (PCB) tells you how much will be the luminous output of LED when operated on particular current


NICHIA is a Japanese LED brand, offering a broad range of SMD LEDs for general lighting applications with high colour rendering index, long lifetime and high lumens efficacy. NICHIA research designing of LED chips, the manufacture and markets LED all over the world used in all types of lighting applications.

Toyoda Gosei

The Japanese manufacturer is one of the best-LED chips manufacturers when it comes to quality of light. As Toyoda Gosei used the same phosphor as Niticha, they can deliver superior light quality. The latest innovation from Toyoda Gosei is the Development of LEDs with light that reproduces natural sunlight based on proprietary technology which comes from mixing red, blue, and green phosphor. This new technology with proved a new level of a comfortable environment for the human, and with highest CRI it will allow people to see colour as if under sunlight. This new technology will fit perfectly within many lighting applications such as fashion retail, art and museum, and inspection proces.


Based in Germany, OSRAM is one of the leading LED chip manufacturers in the world. OSRAM is also world’s largest optoelectronic semiconductors maker after Nichia. OSRAM offers a broad range of LEDs for Automotive industry; for example, Audi using OSRAM LEDs in Headlights of a new model of Audi A8. For general lighting, OSRAM has almost all type of SMD LEDs from 0.1W to 5W, in all dimension packages, i.e. 3030, 5050. 5630, 2835 and others. OSRAM website also has a separate section of Tools and services, which contains different tools and calculators which can help designers to choose best SMD product for their luminaire to achieve best results.

Seoul Semiconductor

South Korean LED manufacturer, Seoul Semiconductor develops LED chips for general lighting, automotive lighting and backlighting. Seoul Semiconductor is fourth largest LED manufacturer in the world. With a wide range of LEDs, their LEDs are very cost effective, high efficiency and long life. Seoul Semiconductor developed world’s first high voltage AC driven LED.

LG Innotek

Coming from South Korea LG Innotek is one of the best manufacturers of LED chips. LG Innotek is also an OEM supplier for SMD chips for manufacturers like Philips and Tridonic which reflect the level of quality and high technology the Korean brand can offer. Their product portfolio contains a broad range of both SMD and COB led chips. Additionally, Innotek also produce LED Lighting Module Engine for indoor applications such as office and retail, and outdoor Modules for street and flood lighting。

Edison Opto

One of the global leading high power LED chip manufacturer. From Taiwan, Edison Opto product range includes SMD LED chip in all packages, i.e. 3030, 2835, 5050, 5630 etc. and high power SMD LED chips in 3535 package. Edison is also manufacturing COB for high power applications up to 200W. Edison major products are a high power LED chips used in lighting equipment, such as indoor lighting, e.g. Bulbs, down lights, panel lights etc., special lighting, and outdoor lighting, e.g. Street lighting applications. Edison also manufactures individual LEDs for Automobile applications.


EPISTAR is a wafer manufacturer; different companies buy wafer which using for LED manufacturing. You can find different Epistar LEDs available in the market from different vendors/manufacturers.Epistar LEDs chips is a good affordable selection for in indoor lighting applications, e.g. LED Bulbs, LED downlights etc., while most of the COB chips are used in outdoor applications, e.g. Floodlights, street lights, tunnel lights etc.  Epistar LEDs chips are available in all regular dimensions and packages, i.e. 3535, 5050, 5630 and most commonly used 2835.

San’an Optoelectronics

Based in China, San’an is the leading, and most selling LED chip brand in China. Most of the LED lighting products manufactured in China uses San’an Chips in them. San’an produce LED chips of all packages that can be used in indoor, outdoor and all general lighting applications.

Chapter 4: Where LEDs being used for?

What are LED used for?

LEDs are mostly used for two things: illumination and indication. These are technical words but are good to understand because if you want an LED for one thing and you buy the wrong thing you’ll be pretty bummed. Illumination means to “shine light onto something” – like a flashlight or headlights, car light, display lighting and home lighting, lighting and buls we can see anywhere.

The major uses of LED (Light Emitting Diodes) is to illuminate objects and even places. Its application is everywhere due to its compact size, low consumption of energy, extended lifetime and flexibility in terms of use in various applications.

Applications and Uses of LEDs can be seen in:

  • TV Backlighting
  • Smartphone Backlighting
  • LED displays
  • Automotive Lighting
  • Dimming of lights

The uses and functions of LEDs depends upon the place where it is used, some examples are mentioned below:

LEDs used for TV Backlighting

A TV’s backlight is the major power consuming source. Uses of LEDs can give a efficient power reduction. In the edges of TV, using an LED will be a cost reduction choice. Using LEDs directly behind the display provides better contrast. LEDs has been replacing CFLs and LCDs when it comes to TV backlighting.

what is TV Backlighting

Smartphone Backlighting

With the use of LED, the backlight design of the smartphone can be thinner and be made within low cost. The price of LED may vary according to the size of the smartphone display. Due to the lower output voltage, they ensure longer battery life.

Smartphone Backlighting

LED in Displays

LEDs display boards are common now these days and are used outdoors like storage signs, billboards, road signs etc. In sign boards which has multiple languages conveying signals, use of more LEDs will be beneficial in terms of less power consumption.

use of LED in displays

LED used in Automotives

Uses of LEDs in automotive industry is growing. With LEDs, energy is saved and there is a clearer visibility. These are extensively used in back and rear of an automobile for better accessibility. LED lighting can improve safety of pedestrians and driver as it enhances visibility when it is ON, OFF and dimmed in any part of the journey

LED used in automotive lighting

LED used lighting

LEDs are incorporated into bulbs and fixtures for general lighting applications. Small in size, LEDs provide unique design opportunities. Some LED bulb solutions may physically resemble familiar light bulbs and better match the appearance of traditional light bulbs. Some LED light fixtures may have LEDs built in as a permanent light source. There are also hybrid approaches where a non-traditional “bulb” or replaceable light source format is used and specially designed for a unique fixture. LEDs offer a tremendous opportunity for innovation in lighting form factors and fit a wider breadth of applications than traditional lighting technologies.

led used in linear lighting

Brandon Lighting is the professional LED linear lighting fixture manufacturer provides all the different commercial and industrial lighting fixture such as LED Linear Vaportight, LED Linear Wraparound, LED Linear Strip light, LED office suspended fixture, LED architectural lighting and LED Recessed troffer and LED Retrofit kits with UL and DLC certificated.

Chapter 5: LED lighting associations and Standards

LED lighting associations in USA for general lighting

IESNA: the Illuminating Engineering Society of North America, is a nonprofit organization that develops and publishes standards regarding lighting. Headquartered in New York City, United States, IESNA standards are in effect throughout all of North America with its nearly 8,000 members. Internationally, IESNA collaborates with the International Commission on Illumination to promote uniformity with the rest of the world.

what is IESNA?

IEEE-SA: Institute of Electrical and Electronics Engineers Standards Association. IEEE Standards Association (IEEE SA) is a leading consensus building organization that nurtures, develops and advances global technologies, through IEEE. We bring together a broad range of individuals and organizations from a wide range of technical and geographic points of origin to facilitate standards development and standards related collaboration. With collaborative thought leaders in more than 160 countries, we promote innovation, enable the creation and expansion of international markets and help protect health and public safety. Collectively, our work drives the functionality, capabilities and interoperability of a wide range of products and services that transform the way people live, work, and communicate.


what is IEEE-SA

LED lighting Standard organizations

UL : Underwriters Laboratories (UL) is the largest and best known independent, not-for-profit testing laboratory in the world. Based in Northwood, Illinois, UL conducts safety and quality tests on a broad range of products, from fire doors to CCTV cameras. The laboratory provides a full spectrum of conformity and quality assessment services to manufacturers and other organizations. It also assists jurisdictional and provincial authorities, offers educational materials to consumers, and works to strengthen safety systems around the world. UL provides comprehensive diagnostic testing services in the following areas: fire testing; medical device testing; EPH services (food service equipment, drinking water certification, plumbing equipment); audio/video; home electronics; Source Verification and Inspection Services (SVIS); electric vehicle components and systems; EMC testing and certification; information technology equipment (ITE) industry services; and telecom industry services. It conducts tests on products in these areas to see whether they meet standards set by UL engineers in conjunction with input from manufacturers and product users, but it will also test products to see whether they meet standards set by outside entities, such as a city (in the case of building codes, for instance). In 2005, UL conducted 97,915 product evaluations in 62 laboratory facilities that it operated around the world. As of 2005, there are 20 billion products that carry the UL Mark.

ANSI: The American National Standards Institute (ANSI) is a private, not-for-profit organization dedicated to supporting the U.S. voluntary standards and conformity assessment system and strengthening its impact, both domestically and internationallyWhether at home or abroad, ANSI is committed to enhancing the global competitiveness of U.S. business and quality of life by providing a framework for fair standards development and quality conformity assessment systems, and safeguarding their integrity. Encompassing practically every industry, the Institute represents the diverse interests of more than 270,000 companies and organizations, and 30 million professionals worldwide..

US Government Regulations or Specifications for LED Lighting

Federal government – EPA:

ENERGY STAR luminaires: The ENERGY STAR Luminaires Specification Version 2.2 was finalized on August 15, 2019. Following is the Version 2.2 product specification for ENERGY STAR certified Luminaires. A product shall meet all of the identified criteria if it is to earn the ENERGY STAR.  To certify a luminaire for ENERGY STAR, first determine which requirements in this document are applicable to the specific luminaire. ENERGY STAR requirements are specific to luminaires classified by the program as directional or non-directional. This specification is generally organized by the requirements, not by luminaire type such as indoor or outdoor, or by light source technology. Partners are advised to review each section, and take note of exceptions where specific performance criteria need not be evaluated; for instance, some color exceptions are in place for outdoor luminaires. Click here to DOWNLOAD the whole ENERGY STAR® Program Requirements Product Specification for Luminaires (Light Fixtures) Eligibility Criteria Version 2.2.

Lighting products that have earned the ENERGY STAR certification deliver exceptional features, while using less energy. Saving energy helps you save money on utility bills and protect the environment by reducing greenhouse gas emissions in the fight against climate change. Light fixtures that have earned the ENERGY STAR certification translate to quality, cutting edge design and the latest in efficient technology.

ENERGY STAR Certified Fixtures:

  • Use 90% less energy than traditional models using incandescent light bulbs.
  • Distribute light more efficiently and effectively — with custom design around the efficient light source to get the best performance.
  • Come in hundreds of decorative styles including portable fixtures — such as table, desk and floor lamps — and hard-wired options such as front porch, dining room, kitchen ceiling and under-cabinet, hallway ceiling and wall, bathroom vanity fixtures, and more
  • Deliver convenient features such as dimming on some indoor models and automatic daylight shut-off and motion sensors on outdoor models.
  • Last 15 times longer and come with a manufacturer-back warranty of at least three years.

ENERGY STAR® lamps: ENERGY STAR Lamps Specification Version 2.1 was finalized on December 31, 2015. The Lamps V2.1 specification will replace the Lamps V1.1 specification on January 2, 2017.

Earning the ENERGY STAR certification means the product meets strict energy efficiency guidelines set by the US Environmental Protection Agency. Lighting products that have earned the ENERGY STAR label deliver exceptional features, while using less energy. Saving energy helps you save money on utility bills and protects the environment by reducing greenhouse gas emissions.

ENERGY STAR Certified Light Bulbs:

  • Use up to 90% less energy than standard bulbs
  • Last at least 15 times longer and saves about $55 in electricity costs over its lifetime
  • Meet strict quality and efficiency standards that are tested by accredited labs and certified by a third party
  • Produce about 70-90% less heat, so it’s safer to operate and can cut energy costs associated with home cooling

Purposes of LED & SSL Standards and Specifications:

• Product safety
– Ensure LED product safety: tests, requirements, and certifications
• Testing methods
– Describe consistent methods to test LED and SSL products
• Performance requirements
– Define performance related characteristics
• US governmental programs specifications
– ENERGY STAR®: Qualify products for energy saving and consumers (users)
– Consortiums: DLC, CBEA, MSSLC, etc.: Specify energy saving and products
performance requirements
– State (CA, MA, etc.): Regulate energy saving products
– AHJ: Ensure public safety or environment protection

Industry’s Standards for LED Lighting

ANSI Standard: ANSI/IES RP-16-10

– To establish definitions for solid-state lighting devices and their components to ensure a common understanding of the terminology
• Status
– Published
– Continuous revisions
• Commonly used terminologies
– LED package
– LED array or module
– LED driver & LED driver class II
– LED lamp integrated & non-integrated
– LED light engine
– LED luminaire

ANSI Standard: ANSI C78.377-2011

– To communicate the indoor lighting SSL products color characteristics to SSL producers and users
• Status
– New revision published
– Ad hoc to be formed for next revision
• Clarification
– Lighting products outside of “color zone” ≠ poor color quality
– Lighting products meeting this standard ≠ color
– The standard does not reflect users visual preference, acceptability, and adoptability for white color
– ANSI standard is not the same as for the Energy Star requirements

about nominal CCT categories

Chromaticity Tolerances

Quadrangle for a nominal CCT
– In both ΔCCT and Duv directions
– Approximately equal to 7-step MacAdam ellipses

what is chromaticity tolerance

Nominal CCT Categories

Nominal CCT: white light chromaticity information of a product
• Requirements
– 8 fixed or selected CCTs, or
– Flexible CCTs with 100 K step

IES Document: IES LM-79-08

– Provide procedures for reproducible measurements of photometry, color and electrical characteristics of SSL products
• Status
– Published
– Revision in process
• What can be tested with this standard?
– Total luminous flux
– Luminous intensity
– Zonal lumen summation
– CCT (Correlated Color Temperature)
– CRI (Color Rendering Index)
– Chromaticity Coordinates (x,y and u’,v’)
– Spatial uniformity of color

Test Requirements

Absolute photometry
– Luminaire (or other SSL product) is referenced to a calibrated standard lamp
– No luminous efficiency calculations or comparisons
• Testing procedures
– No seasoning
– Thermal stabilization
– Ambient temperature 25oC ± 1oC
– Use of integrating sphere (2π or 4π setup) with spectroradiometer, or with a photometer head (sphere-photometer system)
– Use of goniophotometer with photometer head or spectroradiometer

IES Document: IES LM-80-08 

– Provide methods of the measurement of lumen maintenance of LED packages, arrays and modules
• Status
– Published
– Revision in process
• Clarification
– It does not provide performance requirements
– It does not provide guidance or make any recommendation regarding predictive estimations or extrapolation for lumen maintenance beyond the limits of the lumen maintenance determined from actual measurements

Test Requirements: Proposed Revisions
• Extend scope to include photon flux and radiant flux maintenance
– For blue or UV LEDs so test data may be used with remote phosphor testing
– For LEDs used in horticultural applications
• Extend to wide range of LEDs
– Current of voltage controlled LEDs
• Test procedure
– Shall be tested for at least 6,000 hours with data collection at a minimum of every 1,000 hours
– Test two case temperatures Ts, recommend nominal 55°C and 85°C.
– The case temperature and drive current selected by the manufacturer shouldrepresent their expectation and be within recommended operating temperature range.

LM-80 Test Report (to be updated)
• Contents to be included
– Number of LED sources tested
– Description of LED sources
– Description of auxiliary equipment
– Test duration
– Ambient conditions including airflow, temperature and relative humidity
– Case temperature (test point temperature)
– Drive level
– Initial flux and forward voltage at photometric measurement current
– Flux maintenance data for each individual LED light source
– Observation of LED light source failures including the failure conditions and time of failure
– LED light source monitoring interval
– Flux measurement uncertainty
– Chromaticity or wavelength shift reported over the measurement time.

IES Document: IES TM-21-11
• Purpose
– Provide a calculation tool to interpret the datacollected from LM-80 testing; to provide users with lumen maintenance life (e.g., L70) projection, or to predict estimated lumen output values at a given time duration; to interpolate lumen maintenance behaviors for the in-situ temperature (different from testing temperature)
• Status
– Published
• Clarification
– It does not provide performance requirements
– It does not give the criteria if a product is good or bad
– It only addresses lumen maintenance, not rated life or reliability of the products

Chapter 6: The types of LED linear lighting

What’s the types of LED linear lighting?

LED strips

An LED strip light is a flexible circuit board that is populated with LEDs that you can stick almost anywhere you want to add powerful lighting in a variety of colors and brightnesses. LED strip lighting is a type of light that is made up of a series of LEDs set into a strip that is then affixed to a surface.  An LED is a light emitting diode, and they are known for the bright light they produce as well as the different colours of light that you can get.  They are also very energy efficient.  LED lights, and LED strip lighting, are popular because they last for thousands of hours of use, so they never need replacing.

LED Batten strips lights

LED Batten, alternative to LED strip lights, it’s with compact configuration offers high bright illumination. This new LED batten lights can be used to replace traditional battens with fluorescent lamps. Product length available in 2ft, 4ft, 5ft and 8ft, with options for Sensor, Emergency flexible for general lighting application. The LED batten strip light normally contains the lens, housing and LED components. The LED batten strip light commonly used public areas such car parks, toilets and train stations. These versatile units are popular because of their durability, long lifespan and ease of maintenance, as well as providing a good light output.

LED Strip linear lighting supplier LED Strip linear lighting supplier LED Strip linear lighting supplier

LED Bulb or LED lamp

An LED lamp or LED light bulb is an electric light for use in light fixtures that produces light using one or more light-emitting diodes (LEDs). LED lamps have a lifespan many times longer than equivalent incandescent lamps, and are significantly more efficient than most fluorescent lamps, with some LED chips able to emit up to 303 lumens per watt (as claimed by Cree and some other LED manufacturers). However, LED lamps require an electronic LED driver circuit when operated from mains power lines, and losses from this circuit means that the efficiency of the lamp is lower than the efficiency of the LED chips it uses. The most efficient commercially available LED lamps have efficiencies of 200 lumens per watt (Lm/W). The LED lamp market is projected to grow by more than twelve-fold over the next decade, from $2 billion in the beginning of 2014 to $25 billion in 2023, a compound annual growth rate (CAGR) of 25%.

LED Tube lighting

An LED light tube resembles a fluorescent light tube externally and can be used in fluorescent light fixtures, but is made up of a series of LED lights housed within a flexible, non-breakable tube. LED tubes are an energy-saving replacement alternative to traditional fluorescent lights. A Light Emitting Diode (LED) is a low-power, solid-state light that is particularly long lasting and generates very little heat. LED tubes and LED bulbs might be poised to take over where incandescent, fluorescent and compact fluorescent lights (CFLs) left off, barring one or two hurdles. To appreciate LED light technology, first briefly consider traditional bulbs and tubes. LED tubes are often used with office lighting and warehouse applications and can be used in both indirect and parabolic light fixtures. They work well in areas that implement climate control and have standard heights for the ceiling, including storage areas, mechanic garages, and fabrication floors. Therea are T5 LED tube, T8 and T12 LED tubes in the market.Different Types of LED Tubes 1.) Direct Wire or Ballast Bypass LED Tubes, Type B, Simplest Total System 2.) Electronic Ballast Compatible Tubes, TYPE A, Easiest Installation 3.) Hybrid (Electronic Ballast Compatible + Ballast Bypass), TYPE A+B 4.) Universal (T12 Magnetic or T8 Electronic) Ballast Compatible LED Tubes, TYPE C, Best Performance.

LED panel light

An LED panel is an array of individually placed light-emitting diodes (LEDs) that is designed to display specific video patterns and animation from a distance. Original uses for an LED panel include basic billboard advertisements, store signs and gaming displays. More recently, LED panels have been incorporated into general lighting displays because of their versatility over traditional lighting and their lower energy demand LED Panel Light is one of the best lightings product for commercial space and indoor space because of high energy efficient lights. LED Panel Lights are highly luminous because of their lighting arrangement as they have multiple LEDs installed on one board, hence the brightness is definitely more bright and milky LED panels are usually white acrylic or other light diffusing plastic that can be used as backlighting advertising posters or signage. LED panels are lit from the back and some are lit from the perimeter, these edge lit panels are usually thinner.

LED High Bay Low bay lighting

As the name implies, LED high bay lighting is designed specifically to illuminate applications with high ceilings (usually 15-50 feet). The higher the ceiling, the more space is needed to light, so it’s important that these fixtures are powerful and capable of brightening very large areas. Given their placement, LED high bays are generally for commercial and industrial use High bay lighting and low bay lighting are terms used to describe the indoor lighting that is commonly mounted via a pendant or chain, or directly to a ceiling or ceiling girder. Often mounted higher than recessed troffer or fluorescent surface lighting applications, high bay fixtures and low bay fixtures are used in buildings with higher ceilings to provide warehouse lighting, industrial lighting, commercial lighting, retail lighting, and gym lighting.

LED Wrap lights

These commercial ceiling lights feature a prismatic acrylic lens that “wraps around” the lamps and distributes the light evenly in all directions. LED Wrap light is designed to save energy and lower maintenance costs. The LED light engine inside this fixture uses 30% less power to produce the same amount of light as a fluorescent fixture. These surface mounted LED wrap fixtures deliver light from the bottom and sides for all around illumination, unlike most recessed troffers or LED panels which can only emit light downwards. LED wraparound lights consume less power and last longer than their fluorescent equivalents. Wrap around LED light fixtures feature integrated LEDs instead of replaceable bulbs, reducing your maintenance costs. For further savings, some 4-foot LED light fixtures meet DLC requirements and may qualify for local or state rebates. LED wraparound fixtures are suitable for use in wide variety of applications in homes and business.

Cheaper Contractor LED Wrap supplier Cheaper Contractor LED Wrap supplier

LED Architectural lights or LED design lights

LED architectural lighting is an intersection of art (architecture) and technology (lighting). The architecture being illuminated or lighted may be commercial or residential. Other fields of endeavor, such as design, also come into play. Of course, so do physics, engineering and the psychological and physiological effects of light. Architectural lighting design imagines, creates, integrates, infuses and organizes lighting into a coordinated system, including factoring for the fact and advantage of natural light, electrical light, or both, to serve and advance human action.  LED Architectural Lighting are decorative, contemporary lighting fixtures for interior and outdoor areas. From classic modern fixtures to ultramodern looks, LED Architectural Lighting provides high performance, quality, optimal and efficient lighting solutions for the upscale customer.  Light on a higher standard: Sophisticated, Professional, Refined Lighting LED Architectural Lighting fixtures provide a dynamic sense of beauty to your architectural project, incorporating a timeless design for a clean and seamless appearance.

LED Retrofit kits

LED retrofit lighting is simply upgrading your existing lighting to a more efficient alternative. The LED retrofit process of taking out the existing lighting and replacing it with a better quality and more energy efficient option.  It can apply to any kind of light bulb, or any kind of application.  Albeit, residential, commercial, hospitality, industrial, warehouse, small, or big, interior and exterior, the bottom line is that where there is a light bulb, there is a way. Most LED retrofit kits can be easily field installed using no tools with minimum modification to the existing fixtures, eliminating the need for fixture tombstones and ballasts. The LED retrofit kits can be widely used in all the fluorescet light fixture such as strip light, wraparound, vaportight, troffer.

LED Troffer

A troffer is a recessed rectangular lighting fixture designed to fit into a suspended (dropped) tile ceiling. The Department of Energy estimates that over 360 million troffers are installed in the United States in offices, hospitals, educational facilities, and commercial spaces. Troffer lighting (aka recessed troffer lighting) is a term that is often used to describe indoor lighting fixtures that are mounted within a ceiling or ceiling grid, hence the term “recessed.” Typical fixture sizes include 1×4 troffers, 2×2 troffers, and 2×4 troffers. This type of interior lighting is located in a range of building types and workplace usage, and is commonly used to provide illumination for commercial lighting, industrial lighting, retail lighting, warehouse lighting, and classroom lighting applications. LED TROFFER lights are a staple of commercial and industrial lighting and are typically used in hospitals, offices, classrooms, and other workplaces. Troffer lights are usually recessed into the ceiling in a grid pattern to offer bright, even light. But some troffers allow for surface mounting.

LED troffer supplier from China LED troffer supplier from China

LED Vaportight

LED Vapor tight fixtures are specially designed to not only to provide protection and reliability for any space, but to save energy as well. These fixtures are suitable to keep moisture and vapors from entering inside the fixture at any time. Energy-efficient vapor tight LED fixtures are built for powerful lighting in harsh environments, protecting the light source from dust, dirt, and moisture. LED vapor tight fixtures are lightweight to help make installation easier, and can be surface mounted or suspended. Some LED vapor tight fixtures include a motion sensor, allowing the light to come on only when movement is detected. These sensors turn the light back off after a set amount of time without activity. A few fixtures are available with a built in emergency backup that provides light for up to 90 minutes in the event of a power failure. This enclosed and gasketed luminaire is easy to clean and service for wash down areas, industrial facilities, manufacturing facilities, food processing, refrigeration, parking garages and other commercial applications. Please note that there is a significant difference between vapor-tight and vapor-proof LED fixtures. The vapor-proof designation means that the light source will be protected from hazards like corrosive fumes, non-combustible dust, moisture, non-explosive vapors and gases.

LED Vaporproof

When comparing lamps and light fixtures, vapor proof fixtures typically feature durable die-cast housings for specific applications, such as outdoor lighting where the lamp socket and its wiring are protected from rain, moisture, non-combustible dusts, corrosive fumes and non-explosive vapors and gases

LED Shop light

LED shop lights are great lighting options for lighting a small work area or workbench. LED shop lights are the new LED version of fluorescent shop lights. Shop lights are commonly used in garages and workshops (hence the name) where a simple but cost-effective lighting fixture is needed to illuminate a small area such as a tabletop or workbench LED shop lights have longer lifetimes and higher efficiency than their fluorescent counterparts, but for the most part adopted the same linear fluorescent form factor and are typically available in 4-ft lengths using a very similar fixture style. LED shop lights are an efficient, bright and long lasting solution for any space.

LED Vanity lighting

Bathroom is a place where we can enjoy the hot water bath; thus, the vanity lighting for bathroom should be waterproof and safe. LED is a good choice because it works under the low voltage of 12V or 24VDC, which minimize the chance of getting electric shock in such the humid environment. LED is also so versatile as we can even have the vanity lights on the mirror to mimic the Hollywood style.

LED Wall pack light

LED wall packs are typically commercial light fixtures that are installed on the sides of buildings, parking garages, building walkways, and other places around commercial buildings. Not only do they provide energy efficient light but are also good security lights for business buildings making them a go to option in today’s commercial lighting industry. LED wall packs, commonly installed on the sides of buildings, are also used in parking garages, tunnels, building entrances and walkways to provide accent and security lighting. While you can turn wall packs on and off manually or install timers, one of the most energy efficient methods for making sure the lights are on only when needed is to connect wall packs to light sensors.

LED Track lights

Track lights are useful to flood big area with light without wiring too many fixtures. One single track has more than one LED lights that looks very stylish and modern that goes right in every single room of your home. You will find out different size, shape and color for LED track lights. Many track light providers also customize it as per the need of client. Track is made up of solid copper conductor rails that help to attach LED bulbs at the position you want. Led track light it is a directional illumination, can be with the continuous track bar install any where. Tracking lights application included Retail shops, showrooms, art galleries, offices, barber shop and dining rooms. It is a popular choice for both residential and commercial projects.

LED Flood light

LED flood lights offer bright white light that spread with broad angle. It is useful to install in warehouses, perimeters of houses, theaters, playgrounds and stadiums. It offers brighter light than CFL or halogen lights. It is budget friendly, reliable and long lasting. LED Flood lights are the all purpose workhorse of lighting.   From portable models for working around your car, to giant arena lighting, to wall wash lights, they can go anywhere.   The ‘flood’ term comes from the pattern of light, a wide angle beam that seems to ‘flood’ an area with light.   Today the flood name is synonymous with wall lights and motion sensor lights, but any light that uses a wide angle can be called a flood light.

LED Street light

LED Street light is one of the useful innovations we have to offer society. Whether it is your society’s personal road or national highways, LED street lights fulfill all requirements with less hassle of installation, brighter light and efficiency. It comes in different size as per the need and shape. It last for more than 12 years so reduce the cost factor for government. An LED street light is a lamp typically composed of many small light-emitting diode bulbs that sits on top of a pole. In general, an LED street light can be used in the same ways traditional street lights are, such as to provide light on roadways, sidewalks and parking areas. LED street lights are increasing in popularity in many areas due to the advantages they offer over traditional, often gas-based, street lights.

LED Sports light

For all sports a good level of modelling is required. Modelling is the effect of light and shadow produced when light flows from one main direction (known as key light) and additional lower levels of lighting flow from other directions (known as fill light), producing a coherent three-dimensional image of a scene. If there is insufficient key light and all the lighting is fill light objects become flat with little discernable detail. If there is insufficient fill light harsh shadowing will occur, obscuring areas in the field of view. Both cases will cause a reduction in the ability of sports participants to correctly see and react to events on the field of play, and will also cause problems for spectators and television cameras.

The LED sports lighting can be used for the following sports:

  • • Football lights
  • • Baseball lights
  • • Basketball lights
  • • Tennis Court Lights
  • • Pickleball lights
  • • Horse riding arena
  • • Other sports

How to make the LED linear lighting?

How to make the LED linear lighting?

Chapter 7: The benefits and disadvantages of LEDs

How LED lighting are different than other light source?

Compared to other common types of lights like incandescent bulbs and CFLs, there are some key differences to consider regarding LEDs. Some of these include:

  • Light Source: LEDs are the size of a fleck of pepper, and a mix of red, green, and blue LEDs is typically 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.

The Benefits of using LED lighting

Benefit #1: Long Lifetime

Easily the most significant advantage of LED linear lighting when compared to traditional lighting solutions is the long lifespan. The average LED lasts 50,000 operating hours to 100,000 operating hours or more. That is 2-4 times as long as most fluorescent, metal halide, and even sodium lights. It is more than 40 times as long as the average incandescent bulb.

Benefit #2: Energy Efficiency

LEDs use less power, with an estimated energy efficiency of over 60% when compared to traditional lighting. Because of the long lifespan of LED lights, the maintenance work is significantly less, meaning you’ll see big energy and operational cost savings.

Benefit #3: Improved Safety

Safety is perhaps the most often overlooked advantage when it comes to LED lighting. The number one hazard when it comes to lighting is the emission of heat. LEDs emit almost no forward heat while traditional bulbs like incandescents convert more than 90% of the total energy used to power them directly into heat.

Benefit #4: Physically Small

The actual LED device is extremely small. Small power devices can be less than a tenth of a single mm2 while larger power devices can still be as small as a mm2. Their small size makes LEDs incredibly adaptable to an infinite number of lighting applications.

Benefit #5: Great CRI

High CRI is generally a desirable characteristic (although of course, it depends on the required application). LEDs generally have very high (good) ratings when it comes to CRI.

Benefit #6: Directional Emissions

LED technology emits light for only 180 degrees. Every other type of light emits light 360 degrees around the source. 360 degree emissions necessitate accessory devices to reflect and/or redirect the light.

Benefit #7: Environmentally friendly

LED lighting reduces pollution in a number of ways. Low energy consumption means fewer CO2 emissions. And, unlike many other lighting products, LEDs don’t contain any toxic materials or chemicals, and are recyclable.

Benefit #8: Durable Quality

LED lights are resistant to shock, vibrations and external impacts, they make great outdoor lighting systems for rough conditions and exposure to weather, wind, rain or even external vandalism, traffic related public exposure and construction or manufacturing sites.

Benefit #9: Zero UV Emissions

LED illumination produces little infrared light and close to no UV emissions. LED lighting is highly suitable not only for goods and materials that are sensitive to heat due to the benefit of little radiated heat emission

Benefit #10: Design Flexibility

LEDs can be combined in any shape to produce highly efficient illumination. Individual LEDs can be dimmed, resulting in a dynamic control of light, color and distribution. Well-designed LED illumination systems can achieve fantastic lighting effects, not only for the eye but also for the mood and the mind:

Benefit #11: Instant Lighting

LEDs provide instant light and illumination; they brighten up when powered on, which has great advantages for infrastructure projects such as traffic and signal lights. In contrast, fluorescent lights don’t provide optimum illumination levels until they run for a few minutes.

Benefit #12: Frequent Switching

LED lights can switch off and on frequently and without affecting the LED’s lifetime or light emission, unlike traditional lighting that may take several seconds to reach full brightness. Also, frequent on/off switching of traditional bulbs drastically reduces operational life expectancy.

Benefit #13: Low-Voltage

A low-voltage power supply is sufficient for LED illumination, making it easy to use LED lighting in outdoor settings by connecting an external solar-energy source. This is a major advantage to using LED technology in remote or rural areas.

Benefit #14: Superior light quality

Our LED luminaires are available in a range of color temperatures for either ‘warm’ or ‘cold’ light and can be ordered with CRI up to 97 – for close-to-perfect color rendering. We have LED luminaires to match your lighting needs.

Benefit #15: Dimmability

LEDs are able to operate at a virtually any percentage of their rated power (0 to 100%). Of note, they do require hardware specific to LED technology in order to dim (meaning you cannot use the dimming equipment for an incandescent bulb or other traditional lighting technology).

The Disadvantages of LEDs lighting

Chapter 8: The LED noun explanation and questions

The questions about LED noun

What is wattage?

Watt (abbreviated W) is the unit corresponding to the rate of energy consumption (or power) in an electric circuit needed in this case to light a light bulb.

What is Lumens?

Lumens are the unit describing the amount of light (energy) as seen by the human eye that is given off by the light bulb. The lumen (symbolized lm) is the International Unit of luminous flux. It is defined in terms of candela steradians. In simple terms, Lumens (denoted by lm) are a measure of the total amount of visible light (to the human eye) from a lamp or light source. The higher the lumen rating the “brighter” the lamp will appear. Lumens measure how much light you are getting from a bulb. More lumens means it’s a brighter light; fewer lumens means it’s a dimmer light.

What is Lux?

Lux is defined as being equivalent to one lumen spread over an area of one square meter. To put it another way, a measurement of lux (light intensity) tells you how many lumens are needed for the area being illuminated.

What is efficiency?

Efficiency is the amount of light that comes out of a light bulb compared to the electrical energy that goes into it. Energy efficient bulbs waste less energy in producing light than less efficient bulbs. Efficiency is an output over an input. Efficacy is related to the efficiency of the light bulb. It is also an output over an input. The output is the lumens of light and the input in power in watts. So, the expression we use to describe the efficacy of our light is “Lumens Per Watt” or lumens divided by watts. Keep in mind, the bigger the efficacy, the more efficient the bulb.

What does correlated color temperature, CCT, mean?

Color temperature defines the color appearance of a white LED. CCT is defined in degrees Kelvin; a warm light is around 2700K, moving to neutral white at around 4000K, and to cool white, at 5000K or more. Note that CCT does not tell you anything about the color rendering ability of the LED.

In what contexts do R-9 values of CRI of LED lamps become important?

CR-9 represents red tones, which are prevalent in skin tones, clothes, vegetable and meat. For make-up rooms, supermarket and grocery meat and vegetable counters, if the same visual freshness as seen with halogens and incandescent lights sources is required, looking into R-9 values of LEDs is a must. Usually, gallery owners and artists will easily note the difference in effect when red tones are prevalent in the art work.

What is a MacAdam Ellipse?

This is an elliptical region on the CIE chromaticity diagram that contains all the colors that are indistinguishable to the average human eye, from the color at the center of the ellipse. Adjacent ellipses are “just distinguishable” in terms of color. This system is used to refine the binning process of LED colors. Slight color differences in the appearance of LED light are measured in MacAdam ellipses or steps.

What is AC

This is Alternating Current. This is the electricity that is used in most homes and commercial spaces. It’s often referred to as line voltage and number differs from country to country. US line voltage is typically 90V-220V, whereas it often averages higher in Europe.

What is DC

This is Direct Current. Most LED strips on the market use low-voltage DC. A transformer or low-voltage battery is often required to step-down the AC voltage to a suitable level for the LED strips, which is normally 12V or 24V DC.

What is CRI and why is it important?

Color Rendering Index (CRI) is the measurement of how colors look under a light source when compared with sunlight. Having information on the CRI of a LED strip light is important because you want to make sure that the colors are being accurately represented by the light source. CRI is measured on a scale from 0-100. A CRI of 80+ is the industry-standard for most applications while a CRI of 90+ tends to be necessary for situations that need color accuracy.

What is Binning?

Simply put, binning is the process of grouping LEDs during production so that they matched with LEDs of the same color sector. For example, all 2700K chips are ‘binned’ together and are separated from chips that have a higher/lower color temperature. Learn more about Binning here.

What is LED pitch?  

LED pitch is the distance between the individual chips on a strip (FPCB). It is absolutely crucial to understand the importance that pitch plays in your project. The shorter the pitch, the more uniform the light tends to be and the less spotting you have.

What is solid-state lighting?

Lighting devices that do not contain moving parts or parts that can break, rupture, shatter, leak, or contaminate the environment. LEDs do not use electrical filaments or gasses to produce light.

What is a goniophotometer? 

A photometric device for testing the luminous intensity distribution, efficiency and luminous flux of luminaires.

What is DesignLights Consortium (DLC)?

DLC is DesignLights Consortium, the governing body that certifies the quality and efficiency of LED Lights. It is a standard similar to Energy Star. Where as Energy Star is for home owner type products, DLC is for commercial grade LED products. A DLC Qualified product may be eligible for rebates. Your local utility designates whether you are eligible for rebates or not, and it varies between utility companies. Currently there are two standard, DLC Standard and DLC Premium. DLC Premium is more efficient and will save you more money in terms of operating costs.

What is the most common reason LEDs fail?

Heat. Heat is the enemy of electronics, the hotter it is, the shorter the light. However, with good design, you can create a light or fixture that can withstand some high heat environments. Typically a fixture or bulb with an external driver will last longer than an integrated fixture thath as the LEDs and driver as one unit.

What component of the LED system is typically the first to fail?

Almost always, it is the driver. That is why it is important to know who makes the driver in the LED fixture or retrofit you purchase. Brand names like Meanwell and Philips are good. A LED product with a 1 or 2 year warranty is an indication of how good the driver is in that product. Typically a good driver should last more than 50,000 hours

How long do LEDs last?

LEDs are notable for being extremely long-lasting products. Many LEDs have a rated life of up to 50,000 hours. This is approximately 50 times longer than a typical incandescent, 20-25 times longer than a typical halogen, and 8-10 times longer than a typical CFL. Used 12 hours a day, a 50,000 bulb will last more than 11 years. Used 8 hours a day, it will last 17 years!

Is there really any difference between a $15 LED fixture and a $25 LED?

Yes. LEDs are very similar to consumer electronics and quality really matters. In order for an LED to function properly and provide an acceptable light output, all of the components must be built to last. It’s always a good idea to buy from a manufacturer and retailer that you’re confident will stand behind the product. If you’d like to learn more about the components and how cheaply-made LEDs stack up against top-quality product.

What is Zhaga?  

Zhaga is an industry-wide consortium aiming to standardize specifications for interfaces between LED luminaires and light engines. The aim is to permit interchangeability between products made by different manufacturers. Zhaga defines test procedures for luminaires and LED light engines so that the luminaire will accept the LED engine.

What are the different types of LED power supplies / drivers?  

LEDs are driven by constant current (350mA, 700mA or 1A) drivers or constant voltage (10V, 12V or 24V) drivers. Constant current drivers fix the current of the system and vary the voltage depending on the load of the LED. Constant voltage drivers require a fixed voltage, and the LED loads are added in parallel across the output of the driver until maximum output currents are reached.

What does a life of 50,000 hours mean in the case of – LEDs?  

50,000 hours would imply 5.7 years if the light is operated for 24 hours in a day, 7.6 years if the lights are on 18 hours per day and 11.4 years for 12 hours a day.

Why is the life of LEDs measured as lumen depreciation?

Unlike conventional light sources that reduce in output and eventually fail, LED products do not normally suddenly fail. Instead, the light output reduces over time. The normal convention is to measure the life from when the output has reduced by 30%, i.e. when there is 70% light output remaining. This is often quoted as the L70 life and is measured in hours.

What are the factors that affect the lifespan of the LEDs?

The thermal management of the LEDs. If LEDs come on a standalone chip, appropriate heat sinks have to be designed to prevent premature failure of LEDs. The electrical stress: Running LEDs at currents higher than specified make the LED run hot. This can happen with wrongly matched drivers. For example, if the driver produces 700mA but the LED needs 350mA, this will put stress onLED and reduce its lifespan. Higher ambient temperatures than the ones that the LED is rated for will reduce its expected life.

Is lifespan reduced if the LEDs are frequently turned on and off?

Unlike discharge lamps, LEDs are semiconductors and their life span is not affected by the number of times they are turned on and off.

What are “cold” and “hot” lumens?  

These terms do not have any photometric or engineering meaning. However, “cold lumens” is the light output of theLED chip alone when it is first switched on. “Hot lumens”, refers to the light output of the LED when it is fully warmed up in the luminaire. The hot lumen value may be 30% – 50% lower than the cold lumen value.

What are tunable white LEDs?  

Tunable white LEDs are light engines that combine individual chips to produce a range of CCT from warm white and cool white.

Why has the color appearance of the LEDs changed after a period of use?

There are several possible reasons why this happens:

  • The LEDs are being overrun by the use of an inappropriate driver.
  • The application temperature is different from the operating temperature noted in the LED datasheet.
  • There may be heat build-up due to improper thermal management. The phosphor may have degraded due to overheating or other reasons.

How many lumens do I need?

There is no firm answer – it will depend on a number of factors including; room size and shape, height of ceilings, colour scheme, type of lamps & fitting, task areas and needs of the user. As a basic guide; below are the lumens required per Sq M (10.76 sq ft) for different room settings. In many cases a mixture of general and task lighting will be required.

Area Lumens/Sq M

Kitchen 300-400

Kitchen (Task) 700-800

Living Room 400-500

Hallway 300

Bedroom 300-400

Bedroom (Task) 700-800

Bathroom 500-600

Bathroom (Task) 700-800

Reading Area 400

What is VF?

Vf describes Forward Voltage; which is the voltage needed to power an LED to produce the desired light output. But, that is assuming that it’s running on the right amount of electrical current.