I understand what both of you are saying, and I agree that if a listing exists this equipment must be listed, and also that building something out of a bunch of listed components doesn't ensure a good end product.
I'm trying to find out where the listings are found. I have usually looked at the UL White Book, but can't seem to find anything applicable. I quickly looked through the FM website and also came up empty. Perhaps there are no promulgated standards for these various devices.
Bob, I did read through the OSHA section and that makes me pay more attention to your statement that almost anything will require some listing. If there's no standard available, option 1, then I go to option 2 which makes it up to the AHJ. Here in New Mexico, the electrical code says that when there's no standard then a licensed engineer can review and approve it. Again I need to find out if there's a standard. The manufacturers say there aren't any, I just want to be sure.
Jim