Worked for many years. The power line in question was either 500,000 or 1,000,000 volt. Can’t remember.
In industrial facilities where there are many power lines running parallel to each other I have seen very high voltages sometimes at 277v on a digital meter. There just isn’t much current.
The BNSF railroad tracks in Montgomery county, Texas, run underneath some high tension power lines. There are three hot lines on those towers and when the utility unbalances the load on the lines, it induces enough energy in the tracks to blow out the track side equipment.
I was there at an insulated joint and, by connecting a wire to one side of the joint, you could write on the other side using the arc. This was when things were normally balanced.
277 VAC is hot to neutral in a 480 V three phase wye configuration. It's used for industrial lighting.