Low voltage switchboards distribute power to panels, MCCs, and critical loads in commercial and industrial sites. 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. IEC 61439 is a standard developed by the International Electrotechnical Commission (IEC) that covers design verification for low-voltage electrical products and assemblies. Busbar design is still resistance/heat engineering: thickness, width, material, and mounting affect performance. A busbar is a metal bar, usually made of copper or aluminum, that carries electricity inside switchgear. It connects. Busbars are the main current-carrying conductors inside a low voltage switchboard, and they strongly influence thermal performance, fault withstand, maintenance safety, and panel footprint.