Complying with multiple standards can be costly, slow down product launch, result in redundant testing and, if requirements are mutually exclusive or conflicting, may require manufacturing different product models. Conversely, requirements or guidelines comprising different standards that apply to the same industries, devices or initiatives (such as efficient energy use) often overlap.

The goal of harmonization is to find these commonalities, identify critical national requirements that need to be retained, and provide a common standard. For businesses, harmonization cuts compliance costs and simplifies the process of meeting requirements. It also reduces complexity for those tasked with testing and auditing standards compliance

UL supports harmonization to minimize redundant or conflicting standards where support for such harmonization exists.

There are two key types of harmonization that take place at UL: international harmonization and regional harmonization.


Typically, international harmonization involves the adoption of an international standard, such as one published by the IEC (International Electrotechnical Commission) or ISO (International Organization for Standardization). International harmonization can also imply the promotion of UL Standards concepts into existing or new IEC and ISO standards.

When support for harmonization of a standard is achieved, then an IEC/ISO-based UL Standard, with appropriate national differences, is developed. UL emphasizes keeping the national differences incorporated in an IEC-based UL Standard to a minimum.


Regional harmonization involves the collaboration and co-publication of common standards by UL and one or more other national standards development organizations. UL has co-publication agreements with several Standards Development Organizations (SDOs) in order to develop common standards. UL has developed procedures and tools to assist with the development of harmonized drafts.


UL prefers to work in partnership with industry to harmonize standards. International harmonization remains an important aspect of UL Standards development. When harmonization has proved to be a viable option, UL will continue to support international harmonization, and UL will continue to identify ways to minimize national differences in the currently published IEC-based UL Standards. Additionally, UL will continue to encourage the participation by interested parties around the globe in the UL Standards development and harmonization process. By including diverse views on UL's Standards Technical Panel, the outcome will be a more globally accepted set of requirements that make a safer, more sustainable world for all.

Watch & Learn video: Purpose and Role of Harmonization Committees



UL is a member of the Council for Harmonization of Electrotechnical Standardization of the Nations of the Americas (CANENA). Click for more information on CANENA.



UL Template for MS Word and User Instructions — As a Standards Developing Organization, UL is continually looking for ways to reduce turnaround time to process documents from inception to publication. UL developed a Word template, designed around the accepted harmonization format. When this Word template is used, UL has the ability to convert these Word documents into SGML — UL's publication language — resulting in a reduction in the time needed to convert a THC draft to a bulletin containing the THC proposals and faster processing of Standards materials.