Posted: Jul 25, 2017 9:36 pm
I read that, too. But, no one was able to support it with tests results. I couldn't find any, either.
All you need to do it go into a motel room with worn sockets....those with ground up fall right out, those with ground down stay in place...the weight of the heavier side ( the prongs ) is supported by the ground plug
Flipped over....it just pulls out/falls out.
It's not obvious on new sockets, very obvious on worn sockets.
Just about every image of one is ground down