How can I tell if an extension cord is damaged and needs to be thrown away?

A hot extension cord is a bad one — heat, smell, and physical changes are reliable red flags. If it feels warm to the touch while in use, there’s likely resistance from damaged conductors, and internal melting is next. A burnt plastic smell means something already cooked inside. Also check for stiffness, discoloration, or a deformed plug with loose prongs — any of these means trash it.