ECN Forum Forums General Topics of the Trade General Discussion Area Custom machine. Where does NEC requirements stop?

Electrical Engineer here. I have had this discussion at work and am trying to wrap my head around it.

Design and build custom machinery for sale in North America. Use the NEC as a basic guideline for sizing conductors and overcurrent protection. Using fine stranded large gauge conductors for power distribution to certain loads. High stand count cable is desired for flexibility during installation and service. Standard crimp lugs are not UL listed for high strand count conductors. Have been using them in this application for years with no history of problems.

Question is: Where does the NEC _REQUIREMENTS_ stop? I say the NEC stops at the system disconnect. Everything past that is the machinery manufacturer's decision.

Another example: RG 175 is UL listed for 35 V. We routinely run 800-1000 VDC thru it for X-Ray detectors. Catalog lists it for use up to 1000V. Are we violating the NEC?

Thanks