Holiday test or a Continuity test is one of the non destructive test method applied on protective coatings to detect unacceptable discontinuities such as pinholes and voids. The test involves checking of an electric circuit to see if current flows to complete the electrical circuit.
Portable holiday detectors are designed for various pipeline, plant, and other surface applications where the inspection surface remains stationary and the detector is moved over the inspection surface. High voltage detectors are used for thicker surface coatings, such as those used on pipelines and other industrial applications. Low voltage, wet sponge detectors are used for thin film applications.