Moderator: If this question has been asked before (which I cannot imagine it hasn't), please just direct me to the answer. Thanks...

I am a Mechanical Engineer with an interest in electricity, so please forgive my ignorance if I mistate anything. I am really curious as to why some electricians put 15 Amp receptacles in with the Ground up, or why do they put the Ground down (which appears to be more common (no electrical pun intended))? I can see the logic of putting the Ground up (if something falls from above, such as a measuring tape onto a plug slightly out of a receptacle, it will likely hit the Ground rather than the Hot), and I can understand that it seems (for some reason) to look better with the "mouth" down and "eyes" up. I also wonder why the Code doesn't control this issue. When a molded plug is put into an inverted receptacle, it places a stress on the conductors inside.