modern protection on power lines do not use thermal Magnetic circuit breakers like the panel in your house. The current passed by a tree branch depends both on

modern protection on power lines do not use thermal Magnetic circuit breakers like the panel in your house. The current passed by a tree branch depends both on the resistance of the branch and the voltage of the line. In the video I linked it was clearly enough of a short to ionize the air and cause an arc that would damage equipment quickly.