Many people do not consider the positioning of US two prong plus ground pin outlets in their homes. Most prefer the two prongs on the top with the ground pin on the bottom. Maybe it is because it makes a surprising looking face that they can relate.
But the decision can be a matter of safety. In a supplement to one of my Popular Mechanics magazine, another DIYer asked this question and the response made sense:
“…A receptacle outlet can be installed either way….I’ve seen two instances in which thin metal objects fell across the hot and neutral prongs of a card plugged into an outlet…”
A child could also possible put a fork across the two prongs and create a dangerous short. However, for large plugs, having the ground at the top could create unnecessary stress on the plug and cause it to prematurely come out of the socket.
Another option would be to place the socket sideways, but that does not work in some installations. I have seen this in some commercial settings.
As always, remember to check with a certified electrician before performing any electrical work and obtain any permits necessary.