Abstract: The disclosure relates to a self-sealing test probe for use in measuring the resistance between a point within an insulated wire and some external point without degrading the conductor insulation integrity. This is accomplished by utilizing a probe in the form of a hypodermic needle, the needle being electrically conductive and being coupled through appropriate circuitry to appropriate metering to determine resistance. The hypodermic is loaded with an appropriate nonelectrically conductive adhesive which, upon and during removal of the probe from the insulation, forces the adhesive through the hollow portion of the probe into the aperture in the insulation formed by the probe, thereby filling the aperture with the adhesive or sealant to fill the pinhole or void caused by the needle penetration. The amount of sealant injected can be preset or automatically metered.