Joe,

Here is another good one. As everyone says, How do you know if it is abandoned? I try to enforce this one and most times I can get most of the old wiring removed. The contractors don't want to spend days and days, tracing out old wire. If the see that it is easily disconnected, then they will usually remove it. There is another good one in the NEC like this. How about "In a workman like manner.." That rule is hard to prove or enforce. ( I feel.)

Harold