IEC 62271-202:2014 specifies the service conditions, rated characteristics, general structural requirements and test methods of high voltage/low voltage or low voltage/high voltage prefabricated substations, which are cable-connected, to be operated from inside (walk-in type) or outside (non-walk-in type) for alternating current of rated voltages above 1 kV and up to and including 52 kV on the high voltage side, and for one or more transformers for service frequencies up to and including 60 Hz for outdoor installation at locations with public accessibility and where protection of personnel is provided. This second edition cancels and replaces the first edition published in 2006. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: a) regarding temperature-rise test an alternative method for liquid filled transformers is (re)introduced and the temperature-rise test method for dry-type transformers is specified more precisely; b) testing procedure for short time and peak withstand current tests are specified more precisely; c) assessment of electromagnetic fields is considered including a type test (optional) according IEC/TR 62271-208:2009; d) influence of the product on the environment is considered (Clause 12); e) internal arc test requirements have been adapted to IEC 62271-200:2011 and requirements for the assessment of pressure relief volumes below the floor / ground has been assigned; f) the method for defining the load factor in an enclosure for liquid filled transformers is extended with different temperature rises for the transformer outside the enclosure (Annex DD); g) for the calculation of the load factor of dry-type transformers in an enclosure the insulation systems according to IEC 60076-1:2011, Tables B.1 and B.2 are worked out in detail.