[markb846]

Not sure about the rules for units, but the rules for locos after ADD dropping the pan were if the driver could see that the carbons were not damaged. He could seek the authority of Locos home depots maintenance supervisor to isolate the ADD, and raise the pan. The location of the pan dropping had to be reported so that the OHLE people could inspect for wire damage.
I was told that when the 86's first started to work over the GE routes a number of ADD induced failures were caused by the height of the contact wire being above the normal limits of the pan ADD, so they may have run about with the ADD's isolated
Today checking that the ADD is not isolated is part of the drivers prep, and the loco cannot be moved if it is found isolated.