Question 13094 of 731 · Texas Journeyman Electrician Exam
A feeder supplies three 460 volt, three-phase motors with table full-load currents of 14 A, 21 A and 34 A. What is the minimum feeder conductor ampacity?
Exactly one answer is correct.
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Correct answer to question 13094
- B: 77.5 A
Explanation
Feeder conductors must carry 125 % of the largest motor plus the sum of the others: 34 x 1.25 + 14 + 21 = 77.5 A. Adding them without the 25 % (69 A) or applying 125 % to all (86.3 A) are the common mistakes.
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