This electric line was constructed of what has been (and is) known of "bow-and-arrow" heavy metal curved crossarms. These became available and sort-of "state-of-the-art" around the early teens and many were heavily constructed with exemplary galvanizing and quality such that they could survive centuries of service.

This was a wooden-crossarm-free sort of line construction. It is conceivable that these metal "crossarms" would be of high advantage...especially if grounded...for safely dispersing lightning voltages/currents down around the insulator and then to its metal pin....and subsequently to ground. As such the insulators acted as lightning arrestors without the least bit of harm to them. The only exception would be multiple direct strikes to the insulator which could otherwise cause thermal damage affecting the overall electrical and physical integrity of the transmission line insulator.

FYI...In almost all instances lightning does not cause insulator failure. Flashovers from such typically divert lightning surges to ground.

However super-heated insulator surfaces from multiple and direct strikes with rain water thus creating "thermal shock" can damage an insulator. Especially some multipart designs whereby the cemented joints are very hardly stressed.

Again, insulator damage owing to lightning is fairly rare. Exact conditions and the construction (and often the age) might play some part with any insulator's survival although porcelain insulators with 100-plus years of service in lighnting-prone areas of the country are still surviving perfectly as new....

Goes to support the fact that the physics of electricity nor lightning are fully understood to this day.

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