Branch Circuits & WiringQuestion 210 of 521
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?
a.90°C
b.75°C
c.60°C
d.55°C
Explanation
Per 110.14(C), the final ampacity cannot exceed the lowest-rated termination — here 75°C. The 90°C rating may be used only for derating math, and 60°C would apply only if the terminals were rated for 60°C.
Law Reference: 2023 NEC §110.14(C)Practice all 521 questions free — no signup required.
Related questions on this topic
- An 8 AWG THHN copper conductor (55 A at the 90°C column) is installed where the ambient temperature is 46–50°C. Using the 90°C correction factor of 0.82, what is the corrected ampacity?
- 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?
- Under what circumstance may the 90°C ampacity column of Table 310.16 be used?
- 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)?
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