The guts of the switch and the terminations were checked for leakage current and passed the engineers report. The main switch was re-certified about a year ago.
I can't see water damaging a copper wire, after all it carries water if it was a pipe. There should be no air so what reaction would the copper face? A little oxide on the surface but there is not enough flow to migrate any oxides so I expect they would stay put. Ice could become a problem but it does not go more than 3 or 4 degrees below freezing here and the load should help to prevent ice forming inside the wire.
Epoxies might be the ticket but how do you get it in? Will they affect the termination or conductivity of the connection? Most methods of preventing water from getting into the building are geared at the raceway or outside of the wire.
Many years ago I had water get into the wire through the notch the electrician placed in the drip loop. It actually allowed a stream of water to spray over the CT's in the metering section. We fixed that with rubber tape just by breaking the surface tension on the wire. that also was non compacted wire.
I am hoping for a tried method that has been proven effective. I am sure there is a solution out there that works but what? even a $5000.00 bill that fixes it is way cheaper than 6 X 90 foot lengths of 500 mcm and 2 of 350 copper plus the digging, pulling and down time in winter.
