Question 13051 of 790 · California General Electrician Exam
Four current-carrying 3/0 AWG THWN-2 copper conductors are installed in a raceway where the ambient is 50 °C. What is the derated ampacity from the 90 °C column?
Exactly one answer is correct.
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Correct answer to question 13051
- C: 147.6 A
Explanation
The 90 °C ampacity of 3/0 copper is 225 A; the 46 to 50 °C factor is 0.82 and four conductors require 80 %: 225 x 0.82 x 0.80 = 147.6 A. Forgetting the 80 % adjustment gives 184.5 A, and forgetting the temperature correction gives 180 A.
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