I built a lake home for some clients and later installed an underground drop to a pedestal with a 240 volt disconnect (exactly like an AC disconnect). From there, the people who built the dock tied into the disconnect to run wire out to the dock.
Then the rains came. The lake rose almost 35 feet in a matter of weeks. More rain. The lake rose to flood stage and submerged the pedestal. Yet power remained to the dock. The pedestal was under about 15' of water, yet did not trip the breaker at the main service. The owner called me and asked if this was dangerous and I said yes, turn off the breaker at the breaker box, which he did.
My question is: why did the breaker not trip when the disconnect was submerged? It is not waterproof by any means.