The present invention relates to a sealed for life Compact Secondary Substation (CSS), which CSS at the high voltage side comprise a Ring Main Unit (RMU) connected to the primary side of a transformer, which transformer at the secondary side is connected a low voltage switch gear. It is the object of the invention to avoid any service or maintains to a CSS during the normal period for life of a CSS. This object can be achieved with a CSS as described in the preamble to claim one if the CSS enclosure is made of watertight material, which material can withstand corrosion at least for its life time, which CSS can be cooled by a cooling system, which cooling system comprises at least one heat exchanger, which CSS can be protected by an extended arc eliminator, which CSS can be connected to a remote control for surveillance and operation, which remote control communicate with a fault protection equipment.