Nowadays the reliable availability of electricity is expected by both industrial and residential consumers. However, the generation, transmission and distribution all pose engineering challenges in adapting to consumers and sustainable directives while maintaining operational safety. The increasing demand for electricity on the consumer side and the growing number of renewable energy sources (RES) on the generation side are supporting the spread of capacity uprating methods. Dynamic Line Rating (DLR) is a novel, cost-effective line management method with which system operators are able to utilize existing power lines with greater efficiency than with traditional techniques. While the use of DLR has many benefits, there are also challenges that system operators have to cope with at system-level implementation. One of the most significant of these challenges is to find the balance between the required infrastructure for DLR implementation and the reliability of the implemented system. The aim of this article is to present a novel methodology for critical span identification based on which the sensor measurements accurately represent the prevailing conditions along the whole overhead line. Contrary to current methods, the proposed critical span analysis method takes into account the clearance of the conductors, which provides compliance with legal requirements. Furthermore, the uncertainty caused by using weather data to determine local conductor annealing is also eliminated with the recommended method. This way a flexible power system can be created that meets current needs, such as the integration of renewable and distributed energy sources or cross-border energy trade, while at the same time it enhances the operational safety of overhead lines.