A moisture-sealing and thermally-isolating miniature implement for terminating a mineral-insulated and metal-sheathed cable and connecting it to a power source, includes a hollow contact prong protruding from one axial end of a metallic heat-sink barrel penetrated from an opposite end by the steel sheath of a heating element cable. The heating element contacts a nickel or nickel clad iron pin that penetrates the prong and is welded to its most distal extremity. The sheath is welded to the proximal end of the barrel by a hermetic brazed joint, and the distal end of the barrel is hermetically plugged around the prong by a metalized alumina ceramic seal. The copper pin is connected to the end of the heating element within the sheath and mineral insulation. The barrel is machined to have a series of deep peripheral grooves that act as thermal conductivity reducing chokes.