According to Eigenvector :

I'm talking about these things
http://news.thomasnet.com/fullstory/28249/612

I note that they're both UL and CSA approved.

I'll also note that push in terminals on outlets are also (still)
approved by UL and CSA, and all of the device connection failures
I've _ever_ seen were push-in. Most of them with aluminum wire
(where push-in has never been legal), but still, some were
copper.

When it comes right down to it, given the right tools[1]/workmanship
for installing on screw terminals or wirenuts, push-in doesn't really
save you much. And I _much_ prefer the higher clamp pressure and
solidity of a screw termination or a good solid wirenut.

For screw terminals my wire stripper has a strategically placed hole
that makes making a small loop at the wire end very easy. A pair of
needle nose pliers works in a pinch.

The proper set of linesman pliers makes quick work of doing the
twists for wirenuts. Some wirenuts are rated _without_ pretwisting.

Note that these devices aren't intended for stranded wire. Only
solid.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.