A conductor thermal model related to CIGRE and IEEE solutions was developed and compared with measurements. Two pylons of a single line were equipped with weather monitoring stations and conductor temperature sensors based on Surface Acoustic Wave (SAW) principle. Also a fiber optic distributed temperature sensing system was installed to provide additional data. Over 2.5 million data points were evaluated. Developed model deviation for more than 99 % of values proved to be ±1 °C for SAW sensor and ±3.5 °C for the fiber optic measurement. Several ampacity determination methods were described from a transmission grid operator’s point of view. Their features were compared in order to show at which planning period they could be useful. A new method for dynamic line rating determination was proposed. Although it reduces maximum ampacity gain, its advantage lies in minimizing measurement systems while retaining relatively stable value and low risk of temperature limit exceeding.