VLF hipoting is not destructive to good insulation and does not lead to premature failures like with DC voltage testing. Using VLF does not cause degradation of the insulation. It does cause existing cable defects, like water trees and splice defects, to break through during the test. If a cable can’t hold 2 – 3 times normal voltage, it is not a good situation. Cause failure at defect locations during a controlled outage or prior to energizing newly installed or repaired cables, find the fault, make the repair, and be left with a good cable. It is AC voltage; what the cable is designed for and experiences during service. Cable is factory tested with AC voltage at levels higher than the field test voltage. When people talk of VLF testing being destructive, it is only destructive in that a defective cable, joint, or splice may fail under test, which is the intent of the test. How can any engineer doubt the efficacy and effectiveness of testing a cable designed to carry AC voltage with AC voltage?