Does anyone have an illustration, or a textbook page, of a Delta breaker, as in Section 408.36 (D)? I know I've seen a picture of one, but can't remember where.
Mike, I have actually installed two (both were SQ D) and removed one from service in my early career. I remember even then they were allowed for "replacement only" which is what we were doing on the ones I remember installing.
Had dealings with one in the early ‘70s. I hadn’t had very much experience in the trade at that time and it took a long time for my boss to explain to me what was happening with the breaker. To the best of my knowledge that was the only one I have ever seen.
I am not sure but I think they were legal up till about the 78 cycle. Does anyone know for sure when they were removed from panels?