47 points
summary: the holes are almost never (purposely) used to secure the plug in the socket. it is often just for manufacturing reasons (but not always, as in this case). it is included in the specifications as an optional feature, so that the holes are not made too big, or in the wrong place.
6 points
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I’m curious why he doesn’t talk about all the patents that specify locking as a feature. Even modern patents reference the features of older ones in their designs if they use them.
He used all modern plugs you would find on houses in 2000+, of course none of them lock the old way. Go grab some from the 20s and 30s.
