Services & DistributionQuestion 23 of 521
Six 3 AWG THHN copper conductors (90 C ampacity 110 A) are in one raceway at 30 C ambient. After the fill adjustment, what is the derated ampacity?
a.110 A
b.77 A
c.88 A
d.100 A
Explanation
With 4-6 current-carrying conductors the 80% adjustment applies: 110 A x 0.80 = 88 A. No temperature correction is needed at 30 C. 77 A wrongly uses 70%, and 110 A/100 A ignore the fill adjustment.
Law Reference: 2023 NEC §310.15(C)(1)Practice all 521 questions free — no signup required.
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