IEC 61439 is a standard developed by the International Electrotechnical Commission (IEC) that covers design verification for low-voltage electrical products and assemblies. The test shall be carried out according to IEC 60068-2-2 Test Bb, at a temperature of 70 °C, with natural air circulation, for a duration of 168 h (7 days) and with a recovery of 96 h (4 days). - The UV radiation causes deterioration of synthetic material use for enclosures. They carry large currents and must be properly sized to ensure safety, performance, and. Busbar design within Medium Voltage (MV) switchgear is a critical aspect, fundamentally ensuring the safe, reliable, and efficient operation of power systems. A busbar is a metal bar, usually made of copper or aluminum, that carries electricity inside switchgear.