Holiday Detector Inspection is a method of non-destructive inspection of punctures in organic coating applied on steel. The proposed methods is only used when the coating is electrically insulated. Principle of Holiday Detector Inspection is based on the application of an electrical potential between the metallic support and a mobile electrode positioned at the surface of the coat-ing to be inspected. The coating being the insulation due to its dielectric features. A fault in the coating allows the flow of a current between the electrode and the metallic support through the air or water. This current flow is re-vealed through a visual or audible signal. The limit is given by the breakdown potential of the dielectric composed by the coating.