An AC adapter having electronics for converting AC electricity to DC voltage is presented herein. The adapter includes an adapter housing, a plug and a built-in extension cord contained within a storage cavity defined by the adapter housing. The extension cord extends from the electronics to the plug. In a first engagement state the plug is mechanically engaged to the adapter housing such that the plug body completely covers the opening into the storage cavity, and the adapter housing and plug are a single structure that may be plugged directly into a wall outlet. In a second engagement state the plug is removed from the mechanical engagement with the adapter housing, and may be plugged into an outlet some distance from the adapter housing as limited by the length of the extension cord, which maintains electrical connection between the plug and the electronics within the adapter housing.