See it frequently. Since it is the grey area of NEC local inspection and the NESC utility co. it is hard to call it a violation. When it fails the electrician pays. I have seen installations that waited years to get connected because of a paper work mix up. It goes along with the romex connector on the end of the conduit run to bond the grounding electrode. Definately a violation. U.L. has yet to establish the current carrying ability of a NM cable conector. Alan--
Years ago, when I was an itty-bitty helper, I was told to use Tomic connectors as temporary connectors when reattaching a service drop.
In case anyone doesn't recognize "Tomic", they're the old-fashioned two-part-plus-screws type of NM cable clamp that we find when doing service upgrades.