I agree that most breakers 30A and over are rated 75 degrees, but the original post said he could not find the markings saying that. Which refers you to 110-14(c)1 for circuits rated(based on breaker size) 100 amps or less to use 60 degree column in T310-16. Now in all likelyhood, the terminals are 75 degree, but I say if the terminals aren't identified for 75 degree, then that section must come into play. strictly speaking. [Linked Image]