Re: Cad Welding
In my case, they are the preferred method; i.e., I spec them. (I was one of several Proposers to get recognized in the NEC).
My bias was developed at a jobsite where we could not get reliable exothermic welds on conductors #6 and larger. Even the manufacture's representative, after spending two days with us, (to show us how to do it right) had no better success then we did.
The welds were often incomplete and had both external pits and internal voids, to the point we couldn't develop confidence that the cross-sectional area was adequate for our needs.
This was a LONG time ago. I'm no longer quite as adamant.