Spark Test

1) A test designed to locate imperfections (usually pin-holes) in the insulation of a wire or cable by application of voltage for a very short period while the wire is being drawn through the electrode field. Cable is passed through a metallic electrode that makes contact with the surface. The electrode is maintained at a high voltage with respect to the cable con­ductor. When a fault in the cable insulant enters the electrode, it is indicated by a spark. 2) A simple method of identifying the approximate carbon content of steel by holding it against a grinding wheel when the type of spark indicates the approximate carbon content. With experience the presence of the common alloying metals can also be identified.