Bob answered the question up at note 2. Lugs are listed for acceptable sizes.
I was just renforcing what Ghost man was saying. IBM used a lot of 400 hz and some young engineer type guys started spreading the same hooey about how skin effect certainly should be a factor at 400hz and we should be using fine stranded wires for the 400hz cables.
They did it under the covers and behind the customer plug but once we started talking to the electricians that same listing problem raised it's ugly head. Regular lugs are not listed for fine strand wire. Then a saner head prevailed in Kingston and ran those same skin effect formulas on 400hz and figured out it would not be a factor for the normal stranding you have in THHN. Anecdotally I can say the fine stranded wire in the IBM cable ran about the same temperature as the THHN. The good side was, when we removed these systems everyone got battery cables for their boats and jummper cables for their cars when we "recycled" those cables
