Section 110.14/Electrical Connections
NEC 110.14 covers terminal temperature ratings and conductor compatibility requirements that directly affect conductor sizing on electrical drawings.
Electrical connections and splices must be made with devices identified for the conductor material and must be properly installed. Connection temperatures must not exceed the lowest temperature rating of any connected conductor, terminal, or device. For circuits rated 100 amps or less, or for 14 AWG through 1 AWG conductors, the ampacity must be based on the 60-degree Celsius column of Table 310.16 unless the equipment is listed and marked for higher temperature conductors.
Why this section exists
The temperature rating of a conductor terminal determines how much current the connection can safely handle. Most electrical equipment rated 100 amps or less has terminals rated for 60 degrees Celsius. If a designer sizes a conductor using the 75-degree column of the ampacity table but the equipment terminal is only rated for 60 degrees, the connection will overheat. This section prevents that mismatch by requiring conductor ampacity to be based on the lowest temperature rating in the circuit.
What plan reviewers look for
Plan reviewers check the conductor sizes shown on panel schedules and feeder schedules against the 60-degree column of Table 310.16 for circuits 100 amps or less. If a designer has used the 75-degree column to size a conductor, the reviewer verifies that both the equipment terminals and the conductor insulation are rated for 75 degrees. This is one of the most technically nuanced checks in electrical plan review.
Common violations
Related NEC requirements
Table 310.16 provides the conductor ampacity values for each temperature rating. Section 240.4 covers the overcurrent protection requirements that work in conjunction with conductor sizing. Section 310.15 addresses ampacity adjustments and corrections for ambient temperature and conduit fill that further affect conductor sizing.