According to JGJ 242-2011 Residential Building Electrical Design Code 6. 5, it is stipulated that the protection level of outdoor power supply inlet box is not lower than IP54. When they fail, everything goes dark. That. ents), and the electrical equipment, formed by the internal connections and by the incoming and outgoing termina is regard, there has been an evolution which has resulted in the replacement of the previous Standard IEC 60439 with the present Stand rd IEC 61439. In particular, at international. The IEC 61439 series of standards sets out the regulations for power distribution boards as well as assemblies for power distribution in public networks, construction sites, and for prefabricated busbar trunking and cabling systems. You must make safety your top priority when working with low voltage distribution boxes. the con-trol systems of machines) or even, in the worst case, render it non-functional. Accordingly, in addition to IP protection (protection against dust, contact and water), enclosures must also have an adequate. The European EN 60529 standard and the German DIN 40050 standard, part 9, are, combined, an exhaustive document as concerns the degrees of protection provided by enclosures.