Abstract: A vehicular electrical plug or connector is provided. In another aspect, an electrical connector includes a wire cable having a first end that is permanently connected to a wheeled recreational vehicle, a second end with an outlet-engageable plug thereon, and a switch allowing for a high potential or dielectric withstand test by the vehicle manufacturer in one switch condition, and then the switch allowing for normal use while detecting and/or alerting a user of an electrical ground and/or polarity problem in another switch condition. A further aspect of an electrical connector employs multiple lights on a plug, one of which alerts a user of an electrical ground and/or polarity problem, and another of which is illuminated when electricity is flowing through the plug. Another aspect of a vehicular electrical plug and method of manufacturing same, includes liquid polyurethane fed into a hole in a plug housing which then fills the otherwise open area therein to create a water-resistant seal for the plug.