I agree....I think the water at the other end was just coincidence. Is there any chance you were somehow running more current through the plug than it was designed for (missing or incorrect sized circuit breakers, etc.)?
'04 GMC Sierra 2500HD, CCSB, D/A, MaxBrake, B&W Companion, Retrax Pro, AR Power Steps
2013 Rockwood 8289WS w/Diamond pkg
1969 Camaro RS/SS Convertible
Dad's old 1968 Empi Imp (recently recovered from under 21 years worth of boxes/dust)