Dynamic Line Rating (DLR) is an emerging technology, which provides better utilization of power lines, by using real-time information on the weather parameters to dynamically adjust line rating limits. The power line capacity is highly dependent on its heat balance. The heat balance is influenced by external factors such as wind speed, ambient temperature, humidity, solar radiation and load. DLR analyses have shown high economical and reliability benefits from power system perspective. However, the mechanical stress on the conductor due to differences in thermal expansion characteristics of Aluminum and Steel materials could lead to faster ageing and mechanical damages. The study aims to provide better understanding of the risks associated with DLR application, which can affect conductor’s mechanical lifetime. The reliability analysis of transient expansion and shrinkage of the material has identified the risks to the conductor mechanical strength that are associated with dynamic heating and cooling.