Well, I’m certainly no electrician and I’m unclear what you mean about high tension lines. When I look at the high power transmission lines in my area, they appear bare, i.e., silvery. My friends talk about the need to “shield” electronic devices by encasing them in something like a metal shipping container situated on rubber feet so the container isn’t grounded. Its my understanding that the newest Navy ships are similarly sheilded but thats because they’re designed to survive an EMP pulse that would precede a nuke blast.
“Tension” and voltage are equivalent terms, with voltage more quantitative and tension more qualitative in connotation. Electricity as delivered by the utility to your house is not distributed at the same voltage level at which it will ultimately arrive. It goes out at levels of tens or hundreds of thousands of volts for cross-country distribution, which is stepped down to a few thousand volts for neighborhood distribution, then to a few hundred volts for buildings.
Certainly, good shielding practices can harden systems to flare-induced electrical surges. The shield gets the surge, but whatever is within the shield does not.