Abstract: An electrical extension cord includes a male plug convertible between standard residential or blade-type plug elements and twist-lock blade elements, and a female receptacle plug designed to accommodate both standard and twist-lock male plugs. The male plug includes a pivoting body member having a twist-lock set of blade elements on one end, and a residential or blade-type set of plug elements on the other end, such that the user can selectively rotate the body member to orient the desired set of plug elements outwards for use. The selected set of plug elements are placed in electrical contact with the corresponding common, hot, and ground wires in the extension cord by releasable capture of the terminals of the wires, as by the use of spring contacts at the base of the plug elements. The inventive female plug accommodates both blade-type and twist-lock male plugs by providing fixed, permanent receiving slots for the plug elements of each type.