Freezing rain, which does the most damage, will coat all around the power line, typically, because some of it will be wet enough to run around to the bottom before solidifying.
The OP says “an inch of ice on a power line” so we’re talking about one line, not multiple lines.
Back in the early 90s (maybe late 80’s…I forget) I was in Iowa when an ice storm hit. Very bad one. Caused havoc across the city.
I dunno how it works but the power lines seemed to be encased in ice. Not ice hanging down. But ice all around the cable. My car was covered in ice and my radio antenna (the metal pole that were car antennas back then) wise likewise completely surrounded by ice. And it wasn’t just a little bit of ice. It was kinda thick.
Again, no idea how that all happens but that is my anecdotal experience.
And also drip off the bottom and create a long string of mini-icicles. So the even ice coating may be equivalent to a bigger diameter when the dangly bits are accounted for.
There may be some colloquial confusion in that statement, because many laymen will refer to “the power line” as the amalgamation of wires – electrical, telecom, and otherwise – strung between “telephone” poles. They’re certainly not calling them conductors and line poles. Also, residential overhead service drops in North American systems are generally twisted bundles of three wires, two of which are insulated. Pretty much everyone would call that “a power line” but it’s thicker and can accumulate a lot more ice and weight than even a heavy-gauge primary distribution line. In urban areas that 3-wire bundle may also run pole-to-pole serving multiple homes and street lights.
Looking out the window from the dentist’s office the other day I saw a heavy power line passing through street side tree branches that was easily 2 inches in diameter. I assume the spiral wind apparent through the outer insulation was a reinforcing cable giving it additional strength but 1 inch of ice on top of the cable would have been 2 inches wide doubling the calculation for a cable that thick. I don’t think it extended even 100 meters pole to pole but there must be other heavy lines like that and the ones traversing the greatest distance are probably at least that thick.
Once you get outside of buildings to the electrical distribution network, neutral and ground wires become basically interchangeable. So in a residential service drop, the bare wire is the neutral/ground and the two insulated wires are the hots that are 180º out of phase with each other.
You need more squirrels. Bigger squirrels too.
Some useful math here: