If the panel is on, and the water is contaminated enough to conduct, wouldn't this short the mains causing the PoCo OCPD to trip?
Unlikely. Primary fuses rarely go due to arcing on the secondary. Take a look at
this thread. It makes me wonder what
would cause the primary fuse to open. Last summer, the underground primary behind my house faulted and blew the fuses in the two adjacent padmounts. I heard a loud pop in the back yard, and I knew it was a primary fuse. I called the utility and told them exactly which transformers were dead, then I waited up until about 12:30 AM to watch the lineman work. He blew two fuses trying to get the fault to clear itself, then finally bolted it and took out the entire street. That's when he said he needed backup. The power came on shortly after I went to bed. They must have cut out the bad cable. I saw the new one laid out near a manhole at the end of the block the next week.
I guess a bolted short on the secondary transformer bushings might blow the fuse, but after looking at
these photos... well, I always was careful about how I brace my masts, but nothing like an eye-opener!
