Busbar current capacity depends on: Current density guideline (copper, conservative): 1. 5 A/mm² for continuous duty (enclosed environments) Example: Required continuous current = 300A Target current density = 2 A/mm² Required cross-sectional area: [ A = frac {I} {J} ] [ . 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. These standards specify the parameters that should be considered when sizing busbars, including current rating, short-circuit. Rated voltage does not exceed 1 000 V AC or 1500 V DC. Electrical equipment of. 1) One package contains 2 busbar supports including inlay parts for bar thickness 5 mm and lateral finger-safe covers. 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. Behind every reliable low voltage switchgear lineup is a design balance that is harder than it first appears: current must flow safely, heat must be controlled, internal space must stay usable, and the assembly must still be practical to manufacture, install, and maintain.