Branch Circuits & WiringQuestion 211 of 521
Under what circumstance may the 90°C ampacity column of Table 310.16 be used?
a.For final conductor sizing at the terminals
b.For the branch-circuit load calculation
c.Only for applying adjustment and correction (derating) factors
d.It may never be used
Explanation
The 90°C column serves only as the starting point for adjustment and correction factors, provided the conductor is 90°C rated. The final ampacity is still limited by the termination temperature per 110.14(C), so it cannot set the final size directly.
Law Reference: 2023 NEC §110.14(C)Practice all 521 questions free — no signup required.
Related questions on this topic
- Six current-carrying 10 AWG THHN copper conductors (40 A at 90°C) run in a raceway at 40°C ambient. Applying the 0.91 ambient correction and the 0.80 conductor-count adjustment, what is the resulting ampacity?
- For a branch circuit rated 100 A or less, which temperature column must be used for conductor ampacity at the terminations unless the equipment or terminals are listed for a higher temperature?
- A 90°C-rated conductor is terminated on equipment whose lugs are listed for 75°C. Which temperature column limits the conductor's final ampacity at that termination?
- Per Table 310.16, what is the ampacity of an 8 AWG copper THHN conductor in the 90°C column?
- Per Table 310.16, what is the ampacity of a 12 AWG copper conductor in the 75°C column (before any small-conductor overcurrent limit)?
- Per Table 310.16, what is the ampacity of a 10 AWG copper conductor in the 60°C column?
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