[quickthrowman]

True, you can easily hand tighten to 40 inch pounds.

After looking at some more evidence, I agree that it’s probably just a poorly designed receptacle, probably on par with a residential 5-15R which are made to a much lower standard than a comparable commercial 5-15R.

It looks like Leviton may have discontinued the receptacle that lots of people had melt on them so that probably is the case.

[Kirby64]

The 279 outlet is just replaced by the 279-s00. I don’t think there’s much meaningful difference for Leviton outlets. It’s just similar to residential vs commercial ad you state.