Abstract: An electrical connector having a receptacle assembly and a plug assembly with electrically connectable contact pins, from which atmospheric air is essentially excluded by an arrangement of dielectric seals. A first contact pin, in the plug assembly, is encased by a first dielectric sleeve of relatively non-resilient material, and a second dielectric sleeve, of resilient material, is installed in the receptacle assembly and is dimensioned to provide a continuous dielectric seal between the first dielectric sleeve and the body of the receptacle assembly, which is also of a dielectric material. The connector is coupled by inserting the first dielectric sleeve of the plug assembly into the second dielectric sleeve of the receptacle assembly, thereby completing the continuous dielectric seal, but avoiding abrasive contact with the receptacle body and minimizing the axial force needed to effect coupling and uncoupling.