Enclosed busbar systems house all phases in an insulated channel, improving safety and meeting international standards. By Size and Rating: Standard sizes include 30 mm, 40 mm, 60 mm, 100 mm, and 185 mm systems. GRL's Low-Voltage Enclosed Busbar System exemplifies these benefits: It eliminates drilling and cuts installation time and cabinet space by up. Guide to Low Voltage Busbar Trunking Systems Verified to BS EN 61439-6 Guide to Low Voltage Busbar Trunking Systems Verified to BS EN 61439-6 November 2014 Guide to Low Voltage Busbar Trunking Systems Verified to BS EN 61439-6 Companies involved in the preparation of this Guide Acknowledgements. 1) One package contains 2 busbar supports including inlay parts for bar thickness 5 mm and lateral finger-safe covers. Standard sizes and ratings and a complete line of components allow each system to be tailored to suit the requirements of each application, while at the same time provide the. IEC 61439 is a standard developed by the International Electrotechnical Commission (IEC) that covers design verification for low-voltage electrical products and assemblies. This standard defines the design verification, test requirements, and thermal performance of the assemblies. For flexibility and compatibility, we've standardized to two separate manufacturers' depending on the building's location. Buildings in Boulder shall use Legrand's.