Great question — answering as the UphillTech team:
The only true way to check to see if your insulation is damaged is to have someone meg it out for you and check for leakage. That probably will cost less than $700. I can tell you a good contractor would never take a chance to see if it fails, they would either meg it or replace the conductors. Insulation tape is not waterproof so it will do no good unless the interior of the conduit can stay completely dry.
Full answer by Retired Master Electrician: https://diy.stackexchange.com/a/330016 (CC BY-SA 4.0).
Need it done for your business? UphillTech.
