Virgil,
In my former life of a facility manager I did a lot of NTE. That would give you a budget figure to go with, and then if the price came in lower you looked good. But then again I also did job walks and there were far fewer questions than what NC is looking at.
It seems to me that you would bid the job as a complete new re-wire with some cost in for removing the old stuff. Would you accept the liability of leaving in some of the old wiring?
Lawyer: Sparkync, why did my clients house burn down again when our experts have found that there was obiously had some heat stress on this wire.
Sparkync: Looked good to me.
Judge: Judgement for the plantiff.
Unfortunately that is how it is today.
Scot