A Reading Co. electrical instruction book mentioned how many pantographs to be raised per cars in a train. At one time, it was to be just the 1st and last pans, although later the crews would use a few more. A knife switch in a switch cabinet in each power car could cut out the electricity that would open the latch that kept the pantograph down. Since trailer 799 had a pantograph, it also had that switch. I can remember seeing trains freshly coupled together at Reading Terminal, after all the switches were set as desired, lower all raised pans, and then raise only the intended ones.