A product that I have used for years is Grote Ultra-Seal it is a non conductive grease that encapsulates the connection to prevent moisture from getting in between the conductive surfaces. I used this stuff in the Coast Guard all the time on receptacles out on the decks. Before a storm or heavy seas I would go to each outlet and put this stuff in the receptacle to prevent sea water from getting in and causing unwanted grounds. It saved me a lot of repair jobs and was well worth it. Hope this helps.