Kjay:
The fittings you reference above are EMT, and used on the EMT, not the NM as I understand Gregs description. 300.15 would be a bad cite.
I tend to say there is nothing to directly cite, unless at the begining of the circuit, there is no 'from-to' connector.
True. It was just something to mull over. My thought was that NM is a separate wiring method with its own installation requirements and listed connectors, etc.
