<p>The invention provides an electrical ring main unit having circuit breaker unit or fuse unit or load break switch or suitable combination thereof and common bus bar assembly. The electrical ring main unit is hermetically sealed and comprises at least one opening suitably located in therein. The opening is provided in the electrical ring main unit to interchangeably accommodate an insulating plug of an insulating plug assembly or an extensible cable bushing of extensible cable bushing assembly.</p>