This study focuses on RELL B, which has 16 outgoing feeders, with the aim of analyzing the effect of contact resistance testing on heat generation in circuit breakers (PMT). These PMTs act as connecting or disconnecting switches in a 20 kV distribution system. High contact resistance values that are not ideal have the potential to affect power loss values, which can cause temperature increases in the form of heat. These power losses not only reduce system efficiency but also impact the performance and reliability of the 20 kV distribution system. The testing was conducted on 16 outgoing feeders using the DMOM-200 S3 device over two consecutive years (2024–2025). The results showed an increase in contact resistance values on some feeders, such as the Sayu feeder, which had the highest average power loss value of 72.4 with an average heat value of 15,005.95 calories in 2024. Meanwhile, in 2025, the Wijen feeder had the highest average power loss value of 73.4 with an average heat value of 15,220.22 calories. The standard used is R<100 (in accordance with P3B O and M PMT/001.01). Using MATLAB software, this study conducted simulations to show that some feeders generate heat exceeding the ideal threshold value of 14,515.20 calories and approaching the standard limit of 20,736.00 calories. This condition indicates a potential risk of damage to the PMT if not addressed with proper maintenance. This study recommends periodic monitoring of resistance values and the use of thermal simulation as a predictive approach to maintaining the reliability of the 20 kV distribution system.