A leakage current is an electric current that, under normal operating conditions, flows through an undesirable current path (such as an enclosure surface) to ground or between the input and output terminals.
This test is often conducted on DUTs that have been subjected to a pre-load, e.g., after a short-circuit test. In these cases, the test is required in a specific sequence by the relevant standards.
Various product standards for electrical devices and components, i.e. IEC / EN 60664-4
Electrical equipment and systems running on low voltage