This part of IEC 62271 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. Prefabricated substations can be situated at ground level or partially or completely below ground level. In general a prefabricated substation comprises an enclosure containing the following electrical components: – power transformers; – high voltage and low voltage switchgear and controlgear; – high voltage and low voltage interconnections; – auxiliary equipment and circuits. However, relevant provisions of this standard are applicable to designs where not all these electrical components exist (for example, an installation consisting of power transformer and low voltage switchgear). Non-prefabricated substations should comply with the applicable requirements of IEC 61936-1:2010.