The reliability of electric lines is crucial to providing good service to our customers. Inspection can help prevent power line interruptions by detecting bad lightning arresters in substations and on distribution lines. Infrared (IR) camera scanning of electric utility systems can identify overheated lightning arresters quickly and accurately. This paper details how the system reliability for Sumter Electric Cooperative has greatly improved due to the early identification of hot arresters before they cause outages to the system. Performing an infrared inspection gives us the data needed to make decisions as to when to change out the arresters. To further understand why lightning arresters fail, our process has been to return the used arresters to the testing lab for study to pinpoint the reasons for failure. We feel that it is important to discover the root cause of arrester heating, which can lead to catastrophic and costly failures. Key Words: infrared, reliability, lightning arresters, root cause, thermography, overheated, hot arresters, surge arreste.