i read a thread here about repairing a transmission lines with a helicopter and i saw it too on TV. i saw there is a visible spark between the wand and the conductor before he clamps it on. One answered that it sparks because the wand cuts magnetic line of force and charges flow.My question is if the charges flow from the wand and you keep it arcing between the conductor for a very long period of time, (just theoretically) will all the charges from the wand transfer to the conductor and how will the wand be affected?(will it slowly decrease to its original size)
thanks

 

I don't think you can maintain the arc for more than an instant. The spark comes from the difference in potential between the helicopter and the transmission line, but is more like a static spark. As soon as the charge imbalance is canceled, that will be the end of current flow. After the transmission line service, the helicopter will give a nice static spark to the ground, as it will be charged to the line voltage.

Aircraft pick up static charge by flying at altitude, where the atmospheric potential is different from at the earth's surface, and by cutting lines of force as they fly. It is a mandatory practice to ground every aircraft before refueling to eliminate a static spark that could ignite fuel vapors. It is also necessary to discharge a helicopter hovering over a landing pad before transferring a passenger or taking on fuel.