The commissioning process on new substation automation systems (SASs) is a critical stage for ascertaining that a system is installed correctly and that it will remain satisfactorily in service for its expected life‐cycle. An outline of different items to be considered in preparation of commissioning tests (also called site tests) and also an approach of test scope include the elements including hardware description, software identification, test instruments, required documentation, engineering tools, planned commissioning tests, nonstructured commissioning tests, and re‐commissioning. Whenever all parts of the system are finally modified, repaired or replaced, re‐commissioning is required to verify that the portions of the system affected function correctly and that the work has not affected other portions of the system. The extent of re‐commissioning required should be determined from the extent of modifications.