OK, don't laugh too hard: I have the Albe manual, but no general manual on how to use electricity with an extension cord. My notes from orientation are poor. I want to plug in my TAB with an extension cord from garage to prevent water freezing. I know there's the plug in on the outside of the trailer. Do I need to use a 3 prong plug in? Do I need to use that thick black electric cord with the huge plug in? I am really at a loss and starting to panic. I do have a small placer heater in the TAB now, using said extension cord through the window. Thanks.