This European Standard covers the oil-immersed single-phase connection assembly of cables for transformers and reactors, designed in accordance with EN60076 series. NOTE In the standard the term \'transformer\' is used as common definition for transformer and reactor. The purpose of EN50299‑1 is to establish for the cable assemblies: the electrical and mechanical requirements, including interchangeability; the limits of supply; the test to be carried out. It complements and amends, if necessary, the relevant IEC standards and applies to oil immersed cable connections, suitable for fluid-filled or dry-type cable terminations. EN50299‑1 does not cover direct cable terminations (see 3.1.1.3), but, in this case, upon agreement between purchaser and supplier, the standard may be used for guidance except for Figure1 and Figure2 which are not applicable. This standard applies to oil-immersed cable cable connection boxes on transformers with highest voltage for equipment U m=72,5kV to 550kV, including the current conductor terminal at the cable sealing end of the transformer.