Yeah. The massive energy from the lines create a field of electricity and thus light up the tubes. They'll only glow when you stick them in the ground, cuz it's completing the loop.
If you stand under the lines and hear buzzing, those lines are probably carrying at least 4kW of power. 1-2 insulators support 115V. 3-5 support 220. 4-8 support 600+. Etc.
There's info on the web that explains what the lines hold and how many insulators are required.
Basically it works the same way as when Benjamin Franklin discovered electricity with his kite. The electrons (electrical field) are so massive in volume that when they connect to ground they create a spark. Well, when you fill the void with a tube, it builds up enough energy to power that tube, and so forth.
Make sense?