Power cables always get hot when the bike is bulk charging. They will get noticeably hot at either end. Things get evern worse when the connectors are getting a little old and corroded. Last year I had my charging cable connected to my daughter's old and a little undersized 25'-long extension cord and the male and female connectors, where the cords were joined, melted and they became fused together. I had to cut the cords apart and ended up buying replacements for both cords. Fortunately the melting didn't affect the charging of my Zero and it was fully charged when I discovered the problem. Also, fortunately, no fire resulted.
So my suggestion is to make sure your power cords are rated to handle at least a 15 amp continuous load and every few years check that their metal connectors are clean and free of corrosion.