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Frequently-Asked Questions (FAQs)

To help provide information on Zhaga and its activities, we have compiled a list of frequently asked questions (FAQs). If you have further questions, please feel free to contact us.

The Zhaga Organization

Who or what is Zhaga?

Zhaga is a global consortium of companies and other organizations from the lighting industry, and was founded in February 2010.

In 2019, the Consortium moved to a new Consortium Agreement with widened scope to better address growth opportunities in the lighting industry related to IoT and service economy. The consortium with the widened scope is oftentimes referred to as the ‘NEW Zhaga’, the signal the new Consortium Agreement,  but also as ‘Zhaga’, to signal the continuity with its predecessor.

What does the word Zhaga stand for?

The word Zhaga is not an acronym and has no intended meaning. It is a waterfall in Sichuan province, China. The Zhaga logo stands for interchangeable LED light sources.

Who initiated the Zhaga consortium?

Zhaga started with broad support from the lighting industry. Twenty-two companies participated in the first meeting of the Zhaga consortium in March 2010. Since then, several hundred companies have joined Zhaga.

View the full list of Zhaga members


What is the definition of "LED light engine"?

Zhaga defines an "LED light engine" or LLE as the combination of one or more LED modules, together with an LED driver (also known as electronic control gear, or ECG).

Some LLEs contain an integrated driver, while some LLEs consist of one or more LED modules together with a separate driver.

Currently, the Zhaga specifications only define the interfaces between an LED light engine and an LED luminaire. The interface specifications do not depend on the type of LED technology used inside the light engine.

By focusing just on the interfaces, the specifications do not unnecessarily restrict the design of the light engine, or the design of the luminaire.

How do you define "modules" and "drivers"?

An "LED module" is a unit containing one or more LEDs that is supplied as a light source. It may contain additional components, e.g. lenses or resistors or ESD protection devices, but it does not include the LED driver.

An "electronic control gear (ECG)", also commonly known as an "LED driver", is a unit that is located between the power supply and one or more LED modules to provide the LED module(s) with an appropriate voltage or current. It may consist of one or more separate components, and may include additional functionalities, such as means for dimming, power-factor correction, or radio interference suppression.

What is a “light-emitting surface”?

The “light-emitting surface (LES)”is the portion of the surface of a LED light engine or LED module through which the light is emitted. The LES has specific dimensions, position and orientation.

The concept of LES was developed by Zhaga and is now widely used throughout the lighting industry.

Removing the arbitrary variation in LES is a key aspect of enabling LED light-source interchangeability.

Zhaga Specifications

How does Zhaga enable interchangeability?

Zhaga develops interface specifications for different LED light engines. These define the interfaces - mechanical, thermal, optical electical and control - between an LED luminaire and an LED light engine. When applied correctly, these specifications ensure interchangeability. For example, Zhaga focuses on the mechanical and thermal fit of the heat sink, the size and height of the light- emitting surface, and the photometric properties regarding different application areas.

Does Zhaga define the performance of LED light engines?

Zhaga does not specify the performance, quality, design or safety aspects of LED light sources. These characteristics are for each LED light source manufacturer to decide for themselves, based on their choice of technology and market approach.

Do the Zhaga specifications restrict design freedom?

The Zhaga interface specifications define only the interaction between the luminaire and the light engine. They do not unnecessarily restrict the design of the light engine, or the design of the luminaire. The specifications allow innovation inside the light engine while keeping the interaction with the luminaire stable.

Will manufacturers have to use the Zhaga specifications in the future?

No, the use of Zhaga specifications is voluntary, and is not mandated by any government or regulator.

Does Zhaga specify the interface between LED modules and drivers?

No, the current Zhaga Books do not specify the interface between the driver and the LED module(s). This decision was made in order to avoid restricting manufacturers' design freedom in this area. 

However, Zhaga recently anncounced that it will investigate the module-driver interface, with a view to enabling independent interchangeability of modules and drivers. See the FAQs below on "Independent interchangeability" or view our news story


Are all Zhaga-based light sources replaceable?

No, Zhaga light sources are interchangeable. The terms “replaceable” and “interchangeable” have different meanings. However, many Zhaga light sources exhibit features that make them easily replaceable. See our article “Replaceable light sources and Zhaga specifications” for a more detailed explanation.

If a luminaire carries the Zhaga logo, does this mean I can replace the module inside?

No, the Zhaga logo on a luminaire indicates that a suitable Zhaga light engine can fit into the luminaire without re-design. In other words, the Zhaga logo signals that the luminaire design is future-proof.  Replacement may be possible, but this is not what is signalled by the Zhaga logo.

Users should consult the luminaire’s lamp-replacement marking and instruction manual to determine if the modules can be replaced.

If I have a Zhaga-certified luminaire and change the LED module, how does this affect the Zhaga certification?

Replacing an LED module in a Zhaga-certified luminaire should not affect the Zhaga certification as long as the structural design of the luminaire does not change.

If I have a Zhaga-certified luminaire and change the LED module, does this affect the performance or lifetime of the luminaire, or the warranty, or safety markings such as UL or CE markings?

The effect of module replacement on the warranty, safety or performance of a particular luminaire design is outside the scope of Zhaga specifications. However, all the factors listed are likely to be affected by changing the module.

Zhaga recommends that replacement of LED modules in a Zhaga-certified luminaire should always be performed in accordance with the OEM markings and instructions.

If my Zhaga-certified luminaire contains a light source with a socket, how do I know that I am replacing the light source with the correct alternative?

Zhaga-certified sockets (and by extension the luminaires that contain such sockets) are provided with electromechanical fit codes. Zhaga-certified luminaires are also provided with thermal ratings. Likewise, Zhaga-certified light engines are provided with corresponding electromechanical fit codes and thermal ratings.

The Zhaga fit codes and ratings can be used by the OEM to communicate the correct light-source alternatives to users. Depending on jurisdiction, the lamp replacement instructions may need to meet additional regulatory or industry norms or standards.

How do I make sure that my luminaire has the same performance after I replace the light source?

The Zhaga specifications do not include performance requirements or limits, so the Zhaga logo cannot be used to convey the meaning of equivalent performance. However, Zhaga provides OEMs with a complete set of mechanical, electrical, thermal, photometric, and control data that can help them to compare performance among different light sources and to specify suitable replacements.

If the luminaire contains modules and a separate driver, can I replace the modules without replacing the driver, or vice versa?

Zhaga specifications do not currently support interchangeability of independent modules and drivers. Since existing Zhaga Books do not define electromechanical parameters between the LED modules and their drivers, the Zhaga datasheet ratings may not be valid if a module is used with an unintended driver.

However, in March 2014 Zhaga announced that it will aim to enable independent interchangeability of LED modules and drivers. See the FAQ section entitled “Full Interchangeability”.


Zhaga position on interoperability

Zhaga position on interoperability

In its most recent Press Release, Zhaga reports on the NEW Zhaga that “Besides creating specifications for electrical, mechanical, optical, thermal interfaces for components to be used in LED luminaires, the NEW Zhaga will include interfaces for smart components such as sensors and connectivity modules in its scope. It will focus on interoperability and will open new business opportunities in digital lighting and service models.”

This document explains the NEW Zhaga position on interoperability.

In the Zhaga use: A component is Interoperable with the rest of the luminaire if the combination can function as intended.

This is consistent with the Cambridge dictionary:  if two products, programs, etc. are interoperable, they can be used together.

The “can” in either definition has an implicit reference to a user competence. Firstly, it refers to an element of information and requires an ability of a user to verify that products could work together and that there are no incompatibilities. Secondly, it refers to an element of operation and requires ability of a user to actually “make things products together”.

Some examples are in order:
• An engineer at an OEM may decide that components are interoperable if he is able to verify that there are no incompatibilities (e.g. thermal through simulations) and if they can be made to function together using the tools at his avail (e.g. after selecting appropriate cables, connectors, etc.) example: Book 7 

• An installer may decide that components are interoperable if he is able to verify that there are no incompatibilities (e.g. thermal via a label, electrical via arithmetic comparisons) and if they can be made to function together using the tools at his avail (e.g. ability to open the luminaire, insulated screw driver, ..)

• An end-user may decide that components are interoperable if he is able to verify that there are no incompatibilities (e.g. a label) and if they can be made to function together without tools. Often, an end-user may trust that products are interoperable if they fit: plug and play; example Book 14 SFS

The NEW Zhaga has several tools to address interoperability

• Interface restrictions – as e.g. used for mechanical aspects of the interface, linear modules shall be 1, 2, or 4 feet nothing else - to ease verification

• The use of connectors and fit systems to ease installation

• Consideration of all aspects of the interface

Full interchangeability

In March 2014, Zhaga announced that it will aim to enable independent interchangeability of LED modules and drivers.
Read the press release

What change is Zhaga announcing?

Zhaga will aim to enable LED modules and drivers that are independently interchangeable. This is in addition to Zhaga’s stated aim to enable interchangeability of LED light engines.

How will this change be achieved?

Future editions of Zhaga interface specifications (Books) will – where appropriate – include references to specifications that define the electrical and mechanical interfaces between LED modules and drivers.

Why is the change necessary?

Currently, Zhaga specifications define interchangeable LED light engines (LLEs). For LLEs having a separate driver, it may not be possible to interchange LED modules from different suppliers without also needing to change the driver, or vice versa.

What issues does this cause?

If the module and driver have to be replaced together, this limits the options of luminaire makers and end users, and may lead to unnecessary replacement of viable components. There is also confusion in the market, because all Zhaga light sources (LLEs and LED modules) are not fully interchangeable.

The change that Zhaga is announcing will offer flexibility by ensuring that drivers and modules are independently interchangeable.

Why hasn’t Zhaga solved this issue before now?

Until now, Zhaga has excluded the electrical interface between the module and the driver from the Zhaga Books. This is because of concerns that defining the interface would limit innovation in both LED modules and drivers.

Why is Zhaga making the change now?

There is strong market demand to resolve the issues described above and ensure that modules and drivers are fully interchangeable.

In the four years since Zhaga was formed, technical solutions have emerged that make it possible to define module-driver interfaces for specific application segments without limiting the innovation in LED module and driver technology.

How long will it take to implement the changes?

Zhaga’s intention is for these specifications to be developed quickly and without unnecessary duplication of efforts in the lighting industry.


What does "interchangeable" mean?

Zhaga considers that two light engines are "interchangeable" when one light source can replace the other light source without any change in the design of the luminaire.

If two different light-engine suppliers offer interchangeable (Zhaga-certified) products, then a luminaire manufacturer can switch from one supplier to another without modifying the manufacturing process of the luminaire.

This can provide many benefits, such as reduced R&D costs for the luminaire maker, and more choice of suppliers. Also, new light engines can be built using the latest LED technology, and these can be incorporated without changing the luminaire design.

Is "interchangeable" the same as "replaceable"?

No. Interchangeable and replaceable are two different concepts. Zhaga focuses only on enabling interchangeability.

A "replaceable" light engine can be removed from the luminaire and replaced with another. Some Zhaga-based light engines may be replaceable in certain circumstances, but this depends on the design of the luminaire as well as the light engine itself.

For more on this subject, see the “REPLACEMENT” section.

Is "interchangeable" the same as "identical"?


Zhaga-compliant LED light engines can have different performance characteristics provided that they meet the interface specifications.

This allows suppliers to use innovative LED technology inside their LED light engines, and enables them to offer differentiated products and to target applications with special requirements.

Of course, this implies that each time a luminaire is fitted with a different interchangeable LED light engine, the luminaire is likely to have different performance characteristics.