Abstract: An electric plug having a central pole including an axially movable contact rod having a forward portion, and a rear portion, and a radial flange between said forward portion and said rear portion; a connector member for connection of an electrical lead; and a helical first spring received on said rear portion of said contact rod and interposed between said radial flange and said connector member to urge said contact rod in a forward direction, wherein said connector member is provided with a first bore slidingly receiving a rear free end portion, thereby providing slidable electric contact between said end portion and said connector member.