Overhead lines and flexible busbars behave differently. They act like cables (catenaries). The standard details the "drop" method and calculates how the conductors swing and clash during a fault.
The standard provides standardized, reproducible calculation methods that are essential for: iec 60865-1 pdf
: To determine the maximum forces and thermal stresses acting on electrical conductors and their supports during a fault. Target Components Overhead lines and flexible busbars behave differently