Section 310.16/Conductor Ampacity Table
NEC Table 310.16 provides conductor ampacity values by size, insulation type, and temperature rating. It is the most referenced table in the NEC.
Table 310.16 lists allowable ampacities of insulated conductors rated up to 2000 volts in raceways, cables, and earth, based on an ambient temperature of 30 degrees Celsius. Ampacities are provided at three temperature ratings: 60, 75, and 90 degrees Celsius. The table applies to installations with no more than three current-carrying conductors in a raceway or cable.
Why this section exists
This table is the foundational reference for conductor sizing in the NEC. It establishes the maximum continuous current a conductor can safely carry without exceeding its insulation temperature rating. The three temperature columns reflect different insulation types and equipment terminal ratings. The correct column depends on both the conductor insulation and the connected equipment per 110.14(C).
What plan reviewers look for
Plan reviewers cross-reference every conductor size on the panel schedule against Table 310.16 to verify adequate ampacity. They check which temperature column was used and verify it matches the equipment terminal ratings per 110.14(C). They look for required derating adjustments for ambient temperature and conduit fill.
Common violations
Related NEC requirements
Section 110.14(C) determines which temperature column applies based on equipment terminal ratings. Section 310.15 provides ambient temperature and conduit fill adjustment tables. Section 240.4 covers overcurrent protection requirements for the sized conductors.