This standard defines the designation, the manufacturing requirements (dimensions, materials, marking, etc.) and the tests to be comply by isolated connectors (straight-joints, branch-joints and terminations) for cables of rated voltage 0,6/1 kV used in underground power distribution systems, mainly for public distribution, with aluminium conductors in accordance with Spanish particular sections of HD 603 and UNE 211603. This standard establishes the characteristics that isolated connections for underground low voltage electrical distribution networks shall comply and the tests that shall pass. This standard is applicable to insulated connections for indoor joints, derivations and terminations for unipolar cables with aluminium conductors, according to the UNE HD 603 Standards Parts 5N and 5X. The designation of the preferred constructions of the accessories of this standard indicates the range of maximum and minimum admissible sections of each model. It does not imply that the accessory is designed to be used in all intermediate sections. This standard is not extended to the connection sets or the connection elements supplied independently, these accessories are governed by the UNE 211029 and UNE 211024 Standards, respectively. NOTE The figures in this standard do not presuppose design as they are only included as a guide.