Holiday testing is also a sort of non destructive testing to locate the pin holes and voids of the coating systems designed for certain services like pipe lines and storage tanks etc. The testing is performed with either high voltage or low voltage equipment inducing the power to the test part. The equipment is an assembly of the probing electrode, power source with on/off control and ground source.
Knowledge of the operator is the most important factor of the test. So Interface Technical Inspection is always focusing in the periodical technical updating of its inspection personnel.