One nit I would pick is that for the 7484, the middle pin is not for ground, but for the neutral conductor. Yes it might eventually get to ground, but it is considered a circuit conductor back to the breaker (or fuse) panel. Note rating of 15A 125/250V AC, 3 Pole, 3 Wire vs 125V 2 pole for the 7593.
In other words the 7484 is designed for use on a 230 volt appliance and the 7593 for 115 volt appliances. That being said doesn't mean people may have used the 7484 on a 115 volt device incorrectly.
Did I manage to make a mountain out of a molehill or what?
John, W9DDD
For future reference,
NEMA ML-3R 3-pin midget twist-lock female
1-11/64" diameter
NOTE - The ground pin is FEMALE
example - Hubbell 7484
NEMA ML-2R 3-pin midget twist-lock female
1-11/64" diameter
NOTE - The ground pin is MALE
example - Hubbell 7593
NEMA ML-1R 2-pin midget twist-lock female - 31/32" dia
NOTE - no ground pin
example - Hubbell 7464V
Having opened my big mouth, I am now sure I have mistyped something - double check to be sure..........
Cheers,