Wagzel:
Your link leads to some great quality Pass and Seymore outlets but only one model (the 6-20 R) is designed to prevent it being used with a common 120 Volt household plug.
Murphy's law: IF someone can plug into an outlet..... they will.
Sure, the Hoover will vacuum better than ever for a couple of seconds, but the smoke and fire is not worth it.
Eldartford's suggestion is better.
The plug he's referring to cannot be mistaken for a 120 Volt nor will the 120 volt plugs fit the slot.