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The general requirements establish assumptions for the temperature ratings of the terminations. These assumptions say in Section 110.14(C) that if conductors are 14 AWG through 1 AWG, they will terminate at the load end on terminals that are rated for 60° C.
An additional assumption is that if the conductor terminates at an overcurrent device rated up to 100 amps, those terminals on the supply end will be assumed to be have 60° C rating.
Terminals for conductors larger than 1 AWG or connecting to overcurrent devices greater than 100 amps are considered to have a 75° C rating.
In any case, the actual marking found on equipment may modify these requirements. So a 100 amp breaker (or even a 30 amp breaker) may have a 75° C marking, in which case the 75° C ratings can be used.
The same thing is true on the load end, because a terminal may say that it's suitable for a higher rating. It's not unusual in heat producing devices like baseboard heaters or luminaires to find a requirement for a termination and conductor type that is more than 75° C.
In some cases, such as a type NM conductor, the highest rating allowed may be 60° C. It is always advised to check the rating for the specific type of conductor being used.
© Hughes Associates,Inc. 2012