The reliability of the electrical distribution system is crucial to ensuring the continuity of energy supply to customers. This study focuses on the installation of an Early Warning System (EWS) for early fault detection in 20kV cubicles within the electrical distribution network in PLN UID Jateng & DIY's operational area. The EWS integrates temperature and humidity sensors with Supervisory Control and Data Acquisition (SCADA) technology, enabling real-time monitoring of cubicle conditions. EWS detects abnormal temperature over to 40°C. Testing demonstrated that the system successfully detected potential issues, such as abnormal temperature and humidity increases over to 40°C, thereby preventing severe damage and reducing the risk of power outages. The implementation of EWS improves the efficiency of condition-based maintenance compared to periodic maintenance methods and minimizes economic losses caused by unserved energy (ENS) and equipment damage. The results of this study provide strategic recommendations for PLN to enhance the reliability and safety of electrical distribution systems through the use of EWS.