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NOTE: This is an unformatted excerpt from our online fire protection training library.

Conductor Selection & Application

Minimum Size to Avoid Overheating Terminals

Minimum Size to Avoid Overheating Terminals, cont.

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.

NOTE: This is an unformatted excerpt from our online fire protection training library.

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