Principally, these requirements are detailed in BS EN 61439-6:2012 and for a more thorough understanding this guide should be read in conjunction with this standard. Note: BS EN 61439-6 is in line with EN 61439-6:2012 and IEC 61439-6;2012. IEC 61439 is a standard developed by the International Electrotechnical Commission (IEC) that covers design verification for low-voltage electrical products and assemblies. The IEC 61439. Rated voltage does not exceed 1 000 V AC or 1500 V DC. Special service conditions, for example in ships and in rail vehicles provided that the other relevant specific requirements are complied with. Electrical equipment of. 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. IEC 60439, the standard for low-voltage switchgear and controlgear assemblies, was under restructuring from the last decade. It serves as a reference for the construction of. The IEC standard for busbar sizing provides detailed guidelines to help engineers select appropriate busbar dimensions.