Reliability-centered maintenance (RCM) is an effective maintenance approach for many industries, yet RCM analytical methods for power distribution system are limited. RCM implementation procedure for power distribution systems is highly dependent on the specific system’s needs despite possible similarity of power distribution systems in different industries. Therefore, RCM implementation should be carefully customized to include systems specific needs. This work builds a RCM model to evaluate maintenance processes for a power distribution system and quantify system’s total reliability, to reduce subjective maintenance process evaluation. System’s critical components are evaluated from the system viewpoint, not from equipment viewpoint, to include specific service needs. This work selected a medium-voltage system to implement the RCM model due to its criticality and complexity for the power system. The needed data for model implementation depended on rational technical-related assumptions considered by different implementation teams (e.g. engineering, maintenance, reliability, etc.). The model is examined in a detailed and elaborate manner to highlight system’s practical and technical features. A case study is presented for a power distribution system in Saudi Arabia. It was found that the type of equipment is a major factor to label equipment as critical. It also addresses the importance to utilize statistical inference to have a successful RCM model implementation when historical records of components status are missing.