I'm confused about T codes and how to apply them. Also, didn't the NEC used to include a table with auto-ignition temperatures? Where can I find this information now? Thank you
It has been a long time (pre-1993) since Class I Groups had a general T Code assigned to them similar to Table 500-8(D)(2) in the 2014 NEC for Class II Groups. It no longer exists for Class II either since 2017. Sections 500-8(D)(1) &(2) INs now tell you where to look for the info (NFPA 497 and 499)
I don’t know who’s responsible for this chart, but some of the material is out of date or inaccurate. With the exception of Group A (acetylene), Groups are not defined by representative materials any longer. See Section 500.6. In addition, Classes are identified with Roman numerals (I, II, or III) rather than Arabic numerals