Great idea for backup!! And doing something to protect outlets from tripping is essential, I think. My electrician hubby put our outside outlets in outdoor rated boxes with code approved covers so I don't really think too much about it - put the plug into the outlet, close the cover, and go about my business! We also have a plastic thingy that we use if we have to have an extension cord out there, like we did last spring for MHP before Ken put the second outlet in the run. I had to run an E-cord from the run, through the pop door into the coop and then plug it in. The thing we got to go around the connection (where the heating pad cord is plugged into the extension cord end) is like a clamshell - you open it, make your connections and lay them inside, then close the cover.
Lol much easier and more fun to just say that
However the one time forever ago when Blooie did say the technical term, I bought one upon her recommendation along with all this and way too many watering nipples (that one isn't really Blooie, I just couldn't decide between vertical, horizontal, or saddle, and had read good about all. Settled on horizontal but I only got 5 of those. Have wayyyy more saddle and vertical LOL)