As soon as new electrical equipment is installed in service, the aging process begins, with the rate depending on the application, environment, maintenance quality, and many other conditions that shorten the life of the equipment. Most of the electrical power equipment in use today have already deteriorated to different degrees; some remain in service for several decades. As soon as the performance of the electrical equipment begins to decline, knowledge about various life extension techniques for electrical equipment becomes very important. Aging electrical equipment are often retrofilled, retrofitted, or rebuilt, which means that either the parts or the whole unit is replaced with new ones. This is a valuable solution near the end of the equipment life or if the conditions are so bad that failure is practically unavoidable or if some parts are obsolete and there is no way to fix them. On the other hand, there is a continuous, affordable, and justified way of keeping the equipment in good and properly working conditions by providing a timely, thorough, and educated maintenance—the best way to extend the life of the equipment is starting as soon as is recommended by the manufacturer after installation. Different approaches to maintain electrical equipment as the means of extending its life in service are presented in this chapter.