It stipulates requirements for enclosure materials, installation dimensions, the mandatory "one equipment, one switch, one RCD" rule, mechanical structure, earthing systems, component selection and marking. secondary unit substation is a close-coupled assembly consisting of enclosed primary high. SR2 enclosures is a complete range of monobloc structures for the construction of small and medium-sized electrical panels, for control and command or small distribution applications. The following electrical ratings are typical: As a result of locating power transformers and their close-coupled. Distribution boxes serve three essential functions in any electrical installation: Safe installation requires corrosion-resistant materials, adequate internal cable space, and quality wiring throughout. A unit that lacks corrosion protection fails within months in humid or chemically aggressive. The guide lists the process of design, assembly and documentation of a low-voltage switchgear assembly in the order of the necessary steps and at the same time assigns to these steps the relevant sections from the standard IEC 61439 / EN 61439. There are three protection systems used to protect low voltage power distribution conductors and equipment.