The use of reliability assessment and prediction in product design, manufacture, and operation has been an evolutionary process. Physics-based modeling and root-cause analysis of failure sites, failure modes, and failure mechanisms have proven to be effective in the prevention and fault detection of product failures over the past decades. Nevertheless, prognostics and health management (PHM) is now the focus of recent activity as noted by the amount of books, articles, and patents. This three-part review aims to give a comprehensive overview of PHM patents from three aspects: PHM for electrical systems, PHM for mechanical systems, and general PHM methodologies. This series of survey papers reviews the history of PHM research in industry and its current status based on U.S. patents from 2000 to 2015; discusses the application of PHM in the design, manufacture, and deployment of equipment in various industries; and presents some of the key research questions which remain to be addressed, with particular attention on the results reported in the last decade. In this part, 114 PHM patents for electrical systems are covered and comprehensively reviewed from the perspective of seven electrical appliances. Several phenomena are summarized through the investigation of U.S. PHM patents from 2000 to 2015. The proportion of the PHM patents for systems increased much more than for components. Compared with single sensor, sensor networks have achieved more applications so that objects are monitored more comprehensively and accurately. In addition, online assessment with on-board solutions is gradually replacing offline assessment of products using downloaded data to realize timely monitoring and troubleshooting.