In running my vacuum cleaner, I have noticed that the plug end of the cord gets warmer than the rest of the cord. Since the wire gauge and current must be the same through the entire length, why would this happen? I have noticed this regardless of the wall socket that I use and it doesn't seem like the wall socket gets hot. Does it imply that the vacuum cleaner cord is defective at the plug end? Perhaps I should test if it still happens when a heavy gauge extension is used and see if any part warms up.