... while everyone agrees that the test number we got shows the cable satisfactory for use ...
I don't agree with that statement. It only shows that there were no faults at the time of the testing. It in no way shows that the cable is satisfactory for use. There could easily be exposed conductor in the raceway, but just not touching anything that is conductive. This could change if the conduit were to fill with water, or when the conductors move around as the result of temperature expansion and contraction. Yes, I know that the use of a megger is a commonly required acceptance test, but is does not prove that the insulation has not been damaged. It just proves the existence or nonexistence of a fault at the time of testing. The assumption is that if the cable is damaged, there will be a fault and that the megger will detect it. It will detect the fault if it exists, but the installation process can damage the insulation without producing an immediate fault. In some cases this insulation damage will never result in a fault, in others it will.
Don
