The basic requirements for qualifying Class 1E equipment with interfaces that are to be used in nuclear power generating stations are described. The principles, procedures, and methods of qualification are covered. These qualification requirements, when met, will confirm the adequacy of the equipment design under normal, abnormal, design basis event, post design basis event, and in-service test conditions for the performance of safety functions. The methods are to be used for qualifying equipment, extending qualification, and updating qualification if the equipment is modified.