Appendix B mentions a shaft with a 1 hour rating.
True. I don't have my code book in front of me but I believe it states "at least a 1 hour rating". Most of what I read talks about conductors with 2 hour ratings and the only one to my knowledge that is UL/ULC certified is MI cable (Pyrotenax). Haven't found anything listed as "1 hour". The only reason I mention this is because if there was a suitable alternative I'm sure a "1 hour" rated conductor would be less expensive than a "2 hour".
