Electric outlet assembly with rotary receptacles

An electric outlet assembly comprising a bottom shell, a top cover shell covered on said bottom shell, an electric cable extended out of said bottom shell and said top cover shell at one side, three metal contact strips arranged in parallel in said bottom shell and connected to respective conductors in said electric extension cable, and a plurality of receptacle and contact holder sets installed in said top cover shell and electrically connected to said metal contact strips and adapted to receive electric plugs, wherein said receptacle and contact holder sets each comprise:

• a contact holder mounted in said bottom shell;
• three annular metal contact plates concentrically mounted on said contact holder and respectively connected to said metal contact strips;
• and
• a rotary receptacle mounted in a respective hole on said top cover shell corresponding to said contact holder and rotatable relative to said contact holder, said rotary receptacle comprising three plug holes, and three metal contact terminals respectively mounted in said plug holes at a bottom side and disposed in contact with said annular contact plates, said metal contact terminals being maintained in contact with said annular metal contacts upon rotary motion of said rotary receptacle relative to said contact holder.