A Busbar Trunking System (BTS) is a factory-built low-voltage power distribution assembly verified under IEC 61439-6. It uses prefabricated busbar sections, joints, tap-off units, and accessories to distribute power safely with defined current ratings and short-circuit withstand. Guide to Low Voltage Busbar Trunking Systems Verified to BS EN 61439-6 Introduction BEAMA is the long established and respected trade association for the electrotechnical sector. Distribution Busbar Trunking: Busbar trunking having tap-off outlets on one or more faces. It provides a modular alternative to cable risers, feeder. IEC 61439 is a standard developed by the International Electrotechnical Commission (IEC) that covers design verification for low-voltage electrical products and assemblies.