(Formal) Inspection is what matters here.I installed mine and i am not a licensed electrician. So, YES, anyone homeowner can here. It is just a 220V outlet.
W/O a trade license, I can't charge other people for these hookups that will be inspected.
As a home-owner (who knows enough to sketch-out and explain what I did), last I checked, I can wire to code on my own home, have it formally inspected, and I'm good.
That said, all sorts of un-qualified people do all sorts of wiring that never gets inspected, using not much more than skipping-rope.
It may even work.... but you don't want to fast fwd to when a fire-inspector is investigating....
Rgds, D.