Specifiers enjoy a choice of brands and components to provide optimal solutions for their applications. Owners can replace components for maintenance or upgrade purposes while retaining the hardware. And manufacturers, specifiers and owners all benefit from having a choice of components from different suppliers with associated economy of competition. 


While integrated light-emitting diode (LED) replacement lamps are designed around conventional lamp sockets, these interfaces are impractical for LED lighting fixtures, the majority of which are designed as highly integrated devices. This allows the product to be optimized around the technology but means the light source and control gear (driver/power supply) cannot be easily replaced. Some products are designed around components that are replaceable but only with major disassembly. A growing number of fixtures are entering the market that offer replaceable components, but the connections are proprietary, providing durability but not choice.


Enter Zhaga, an industry consortium founded in 2010 around the goal of providing interchangeability of LED light sources made by different manufacturers. (The term “Zhaga” is arbitrary; it is the name of a waterfall in Sichuan, China.) The organization now has more than 270 companies and organizations participating, including big names such as Acuity Brands, Cooper, Cree, GE, Osram Sylvania, Philips and Zumtobel.


Zhaga is working on specifications for the mechanical, photometric (light output and distribution), thermal and electronic compatibility of LED modules and systems. These specifications do not cover the internal design of the light source, focusing instead on the interface with other components within the fixture. Source manufacturers will continue to develop and differentiate their products based on features such as light output, efficacy, color quality, beam uniformity and control interfaces.


The specifications have been developed and are available for adoption by Zhaga members. Some specs have been published and may be used by anyone, although only members may get products certified as compliant. In 2012, more than 30 manufacturers displayed Zhaga-compliant LED products at major trade events. Currently, more than 60 products are available in the Zhaga product database at www.zhagastandard.org.


Benefits of standardization


A lighting project has various stakeholders, each of which may benefit from interchangeability of light sources in LED products.


Manufacturers would be freed to do what they do best and do it faster, cheaper and with less risk. Fixture manufacturers, for example, would be able to choose optimal light sources from multiple vendors rather than designing their own sources or buying a custom design, speeding up time-to-market while reducing cost and risk. They would not have to continually upgrade and retest the LEDs in their products. Source manufacturers, meanwhile, could focus on a smaller number of light sources to cover a broad range of applications and OEMs without having to design customer- or application-specific LED light engines. This would increase sales volumes per model, generating economies of scale.


“Interchangeability provides design freedom inside the light engine, accelerating chip-level performance enhancements, and reduces market risk with an installed base of ‘sockets,’” said Steven Pyshos, marketing manager for Zhaga-member Eaton’s Cooper Lighting Division. “It also enables luminaire manufacturers to rapidly implement LED performance improvements and focus on developing new luminaire designs, optimizing performance around selected LED engines.”


Lighting system designers would benefit from greater flexibility in specifying optimal lighting solutions for their clients. 


“Lighting designers will be able to choose from catalogs of interchangeable LED light engines that can fit compatible luminaires,” said Roy Harvey, SSL standards and regulatory affairs officer for Zhaga-member Osram Sylvania. “Different manufacturers that offer products complying with the same standard may offer a higher quality of light, a higher lumen package or an optimal beam pattern, but all will have the same mechanical footprint and thermal interface and fit the same luminaire.”


Distributors would benefit by stocking fewer standardized LED light engines, reducing inventory and risk while providing access to an aftermarket for replacement sources. And owners will enjoy greater confidence and lower risk by investing in future-proof lighting fixtures that incorporate best-in-class LED sources that can be easily serviced for maintenance or upgraded as lighting needs change and LED technology advances.


How will Zhaga impact contractors?


Specifying, installing, maintaining and upgrading Zhaga-compliant LED lighting fixtures will be similar to existing lamps, while providing comfort working with familiar form factors, common interfaces and availability of interchangeable sources.


“Zhaga allows for interchangeability of different modules,” said John Koster, product manager, LED modules for Zhaga-member GE Lighting. “For a contractor, this means that, down the road, there is easier access to service parts, modules that are interchangeable and available from many different manufacturers, faster field installations, better availability, and improved troubleshooting because it’s easier to replace modules [than] to try to isolate the problem.”


Contractors educated about lighting and familiar with available LED light engine products will be in a good consultative position to help customers upgrade Zhaga-compliant LED fixtures. 


“An electrical contractor could have installed a light fixture in 2012, but, by 2015, our LEDs will have evolved to where they’re 30-40 percent more efficient and the cost has come down. So the contractors can justify an upgrade to their customers based on energy savings with a one- to two-year payback,” Koster said.


Beyond energy, owners may want to change their modules seasonally or over time based on desired aspects of performance besides energy savings, such as light output, efficacy, service life or color quality. Note, however, that some Zhaga modules are designed to be installed without the need for tools, wire harnesses or fasteners. Because they twist into place, they can be installed without needing special electrical skills.


Current availability


Products certified as compliant with Zhaga specifications are labeled with a Zhaga (“Z”) logo which may only be earned by members of the consortium. The specifications are divided into eight “books.” Book 1, published in October 2012 and available as a free download at www.zhagastandard.org, provides general information and terminology. Books 2 through 8 include various types of LED light engines with integral or separate control gear. 


Currently, more than 20 products are available for Book 2, which covers socketable LED light engines with integrated control gear. The specification was published in February 2013. The LED light engine has a round drum shape with maximum dimensions of 70.2 mm in diameter and 45 mm high. It has a circular light-emitting surface with a typical diameter of 59 mm and a PHJ65d-type base.


More than 40 products are available for Book 3, which became publicly available October 2012. Book 3 defines the interface for a small round LED light engine suitable for spot lighting and other applications that need a point light source. The LED light engine consists of a nonsocketable disc-shaped LED module designed to be screwed to the heat-sink base of a lighting fixture and controlled by a separately housed LED driver (an optional screwless, locking-ring mounting is also specified). The modules have a diameter of 50 mm and a maximum height of 7.2 mm. For example, Cooper’s IRiS P3LED 3-inch-aperture recessed downlight series (launched in June 2012), is a Book 3-compliant lighting fixture built around this spot LED engine specification.


Products designed around specifications in the other books are on the way. GE expects its Infusion LED modules to carry the Zhaga logo based on compliance with Book 5 specifications for socketable light engines with separate electronic control gear. Osram has developed PrevaLED Core Z2 spot LED (Book 3), PrevaLED Compact flat emitter (Book 4), and PrevaLED Linear Slim (Book 7) indoor linear LED light engines.


Buyer beware


Note that a Zhaga-compliant LED light engine installed in a lighting fixture does not make a Zhaga-compliant LED fixture. Both the light engine and fixture must be tested and should be verified as compatible.


“LED light engines need their luminaires to dissipate the heat generated by the LED light engine. In the test report required for logo certification, LED light engine manufacturers specify how much heat the LED light engine generates and the maximum thermal resistance a compatible luminaire may have,” Harvey said. “Luminaire manufacturers specify each luminaire’s thermal resistance at different power levels. If the thermal resistance is less than required by the LED light engine at the LED light engine’s operating power, the LED light engine and luminaire are compatible.”


Zhaga does not yet cover dimming functionality, which is expected to be addressed in the imminent NEMA standard SSL 7A. Another current shortcoming of Zhaga is it does not cover electrical connections between nonintegrated control gear and the light source. If a control gear internal to the fixture fails and is no longer manufactured, the light engine may need to be replaced along with the control gear. Additionally, if the light source is replaced with one that is ostensibly interchangeable but from a different manufacturer (e.g., Philips to Osram or vice versa), and the driver is a separate component, the driver may need to be replaced.


Zhaga-certified modules and Zhaga-certified fixtures are still subject to any safety regulations, such as UL or the National Electrical Code, and performance requirements, such as DLC and Energy Star, that apply in the region in which the product is installed. Zhaga certification does not test for regulatory or incentive requirements, so any replacement modules from a different vendor would need to meet the requirements for that installed fixture’s application and installation location.


“The concept of the LED light engine consisting of LED array and driver addressed this constraint,” Pyshos said. “However, source manufacturers are now realizing standardizing control gear will be necessary to drive higher levels of adoption.”


What’s next


Zhaga is still in its infancy, so, at this time, it is difficult to speculate whether the initiative will be successful in the marketplace. 


“The future of Zhaga is uncertain,” Pyshos said. “Many of the LED luminaires available today were developed prior to the introduction of Zhaga modules. Market demand for open-platform LED luminaires and broader availability of Zhaga-based platforms will ultimately determine the adoption. Based on the current business model of multiple sources for many common lamp types, it is difficult to envision a future without interchangeability.”


He added that the lighting industry is currently divided regarding implementation of Zhaga, noting that some LED array and driver suppliers and fixture manufacturers continue to push proprietary designs in an attempt to lock up market share while others embrace open standards. He said there is room for both.


“Value-driven LED lighting products leveraging ‘peak’ designs produced in high volumes will deliver ‘good-enough’ performance at low costs and will most likely be replaced at end of life,” Pyshos said. “Specification-grade luminaires extracting the last molecule of performance will benefit from a clear upgrade path made possible through careful engineering and adoption of emergency standards.”


Koster is optimistic about adoption. 


“We now have Zhaga-certified products on the market, so we anticipate that many companies will market Zhaga and promote these products in the next year,” he said. “I think you’re going to see some really good traction around Zhaga in the next year or two, along with more manufacturers adopting the different specifications. That means we will see a lot of different options on the module side with several different manufacturers, and, as a result, the number of Zhaga-certified luminaire manufacturers will start to increase.”


Final word


“Before you install or sell a product, ask to see the Zhaga logo,” Koster said. “If you see the logo, you know you have a product that will be serviceable and supported by many different manufacturers and options.” (The logo is shown on page 86.)


For more information about Zhaga and to learn more about the latest compliant products, visit www.zhagastandard.org.


GE Lighting’s Zhaga-compliant (Book 5) Infusion LED module, is suitable for spotlighting, downlighting, track and accent lighting. Note the “Z” logo on the product, indicating Zhaga compliance.

Cooper Lighting’s Zhaga-compliant (Book 3) P3LED 3-inch LED recessed fixture, an expansion of the company’s IRIS series

Zhaga specifications

In a conventional lighting fixture, lamps and ballasts or transformers connect using industry-standard interfaces, allowing manufacturers to optimize each component separately with efficiencies and innovation gained in specialization.