[Al Skierkiewicz]

As I understand this, these lines are AC voltage and the helicopter acts as a capacitor (plate) to ground, so some potential difference will exist whenever the helicopter and line are not connected. So current does flow albeit in small amounts. You will not find many birds sitting on these high voltage lines for the same reasons. At these voltages, a condition known skin effect may also come into play. The potential is so high that electrons actually start to push away from each other and so are looking for any other path. This is the part that causes you hair to stand up. In these lines, the majority of the electric current actually flows on the outside of the wire. (I am sure there are some power line workers lurking here that can jump in any time.) I have been told that on these lines, the wire is actually a steel core with a conductive jacket to take advantage of the strength of steel and the low loss of a conductive jacket. If you remember back a few years, you could pick up a little arcing from the faceplate of your color picture tube by running your hand over the face of the tube.