SUSTAINABLE ENERGY

Innovating Safety Standards for Energy-Efficient Lighting

UL is advancing the safety standards for LEDs, developing new requirements that effectively address thermal management to minimize the risks of fire posed by LED products today while anticipating future LED product designs and usage.


WHY INNOVATING SAFETY STANDARDS FOR ENERGY-EFFICIENT LIGHTING MATTERS

The light-emitting diodes (LEDs) market is expanding rapidly, largely due to the energy efficiency and long life span of this technology relative to incandescent lighting. While this expansion is in progress, lighting experts are considering the potential safety risks emerging as the industry moves from glass and brass to semiconductor technology. It is important to innovate safety standards for LEDs to facilitate the growth of this sustainable technology. There is a specific need for safety requirements that not only effectively address thermal management to minimize the risks of fire posed by LED products today, but are also effective for future LED product designs and usage.1

Thermal management techniques are needed to address the risk of fire if the heat in an LED light is not safely conducted away from vulnerable parts and materials.

Thermal management techniques
are needed to address the risk of fire
if the heat in an LED light is not safely conducted away from vulnerable
parts and materials.

CONTEXT

According to the U.S. Department of Energy, LED lighting uses 75% less energy, lasts up to 25 times longer than incandescent lighting, and by 2027 will be able to save energy that is equivalent to the annual electrical output of 44 large electric power plants (1,000 megawatts each) in the U.S. alone.2 The sustainability benefits and growth of LED lighting have translated to different applications and technological advances to drive performance. As a result, a McKinsey study now projects 840% growth globally for LED lighting, from $10 billion in 2010 to $94 billion in 2020 when LEDs will account for 60% of the total lighting market.3 Additionally, the LED lighting market is expected to grow at a compound annual growth rate (CAGR) of 36% globally between 2012 and 2016.

 

Lighting products that use LEDs or other solid-state light sources produce heat in a way that is different than that of lighting products that use incandescent or other legacy light sources. Incandescent light sources are known for substantial energy losses, especially due to radiated heat that produces no light. To accommodate this heat, incandescent lamps are made from high-heat-resistant parts such as brass and glass. Over the years, safety design practices were developed to segregate the heat from the other parts of the lighting product. With LED lighting products, the overall energy loss is substantially lower, but high temperatures are generated within small areas of the LED light sources and associated electronics. Thermal management techniques are needed for satisfactory performance of LED light sources, and also to address the risk of fire if heat is not safely conducted away from vulnerable parts and materials. These statistics and technical challenges make a strong case for a need to advance LED safety standards.5

WHAT DID UL DO?

UL saw that LED technology was advancing rapidly and published the first general illumination LED Safety Standard, UL 8750, in 2009. The Standard created a platform of safety requirements for LED lighting equipment as well as the entire supply chain of components used in lighting products employing LED technology.

 

We determined that the most effective and flexible approach would be to develop a “horizontal” standard with requirements relevant to LED technology that could be common to and referenced from the various lighting end-product standards. This approach enables a high degree of consistency in the technical requirements. At the same time, it allows the UL Standards Technical Panel (STP) responsible for the content of each lighting end-product standard to determine what is relevant within the horizontal LED-technology standard for their particular types of lighting products.

 

Our approach involved an innovative and collaborative process with industry representatives (component through end-product producers), trade associations, government agencies (e.g., EPA, DOE, CEC) and users/specifiers to help ensure that product safety kept pace with the fast-moving advances in the LED lighting industry. UL convened an LED Lighting Summit as a forum for dialogue with nearly 100 lighting professionals and thought leaders, which led to the formation of one of our largest standards panels. Discussion topics included “horizontal” versus other standards structures, emerging products, integrating crossover industry products (e.g., power supplies), safety issues and industry plans for interchangeability, all of which resulted in a commitment to keep current.8

 

UL developed a “horizontal” standard approach with requirements relevant to LED technology that could be common to and referenced from the various lighting end-product standards.

UL developed a “horizontal” standard approach with requirements relevant
to LED technology that could be common to and referenced from the various lighting end-product standards.

Since the Summit, UL has published technical requirements that are routinely updated and has stayed abreast of new developments and their implications. STPs continue to regularly bring together key stakeholders to stay on the cutting edge of safety standards. Due to the rapid development of LED technology, revised and new requirements are frequently discussed, debated and developed. The following represent a sample of critical developments on which UL is focusing.9

 

LED FIRE BARRIER CONCERNS In fixed commercial lighting (such as streetlights and high bay fixtures), lenses serve dual purposes. They are relied on as a part of a fire barrier for the electrical product, and they affect the quality of the light exiting from the luminaire. Traditionally, these lenses are made out of glass or certain types of plastic that satisfy the fire barrier concerns but are not the best solution for light quality. With LED lighting, these are known as secondary lenses because there is already a primary lens over the LED package. We have been working with the industry to find alternate methods for evaluation of fire barrier concerns to achieve the desired safety outcome while offering greater flexibility in choosing polymeric lens materials that are known to maintain and enhance light quality.10 

 

COMPONENT INTERCHANGEABILITY With traditional lighting technologies there is a high degree of interchangeability within the major components of a luminaire. This allows manufacturers to continue to innovate new designs using standard “mix and match” parts with known safety and performance characteristics. Although there are concerted attempts at driving interchangeability, this has not been substantially achieved with LED lighting today. Most parts are custom- made to match other specific or proprietary parts that make up the electrical components of a luminaire. We have been working with the industry to facilitate interchangeability with LED drivers (power supplies).11 One expert task group within STP 8750 is focused on simplifying LED driver selection during the initial luminaire design process and in cases where an alternate LED driver would be required during the life of the product.12

 

Many of the LED driver parameters are already covered to a degree by current requirements contained in either UL 8750 or other UL standards. However, there were specific areas where requirements needed to be added to UL 8750, related to the expected ambient and driver operating temperatures. In collaboration with STP members, we conducted laboratory temperature tests on LED drivers to validate assumptions. Based on our findings, a set of new and revised safety requirements were developed.13 

 

UL’s efforts to innovate safety requirements and build consensus around them help us keep pace with LED advancements and mitigate the evolving risks.

UL’s efforts to innovate safety requirements and build consensus around them help us keep pace with LED advancements and mitigate the evolving risks.

CROSSOVER TECHNOLOGY INTEGRATION We are innovating the standard to be flexible enough to integrate information technology equipment (ITE)-type power supplies into lighting systems, where appropriate. The global community of ITE power supply manufacturers observed that their products could be easily reengineered to work as LED drivers. To meet this need we compared the ITE and LED driver technologies, considered the similarities and differences in the use and life span of the products and created a comparison document to identify potential safety gaps. Eventually published as Appendix B of UL 8750, this document identifies the additional requirements for ITE power supplies that already meet the requirements in the Standard for Information Technology Equipment (UL 60950-1) to be used in the lighting application. This document has greatly simplified the process for ITE power supply manufacturers to ensure that their products are safe and compliant with the lighting standards.14 

IMPACT

UL is dedicated to keeping new LED lighting applications “just as safe” as what came before them through our collaborative and integrated approach. The basic safety risks for lighting products using LEDs are comparable to those of lighting products that use other types of light sources — risk of electric shock injury (where hazardous electric current can conduct through a person), fire (where heat can ignite the lighting product or surrounding surfaces) and personal injury. 15 However, there is also a need to minimize hazards specific to LEDs and other solid-state light sources.16 Our efforts to innovate safety requirements and build consensus around them help us keep pace with LED advancements and mitigate the evolving risks

Sources

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