Question 13036 of 749 · Maryland Journeyperson Electrician Exam
A three-phase 208 volt load of 90 A is 150 feet from the source. Ignoring ampacity, what is the smallest copper conductor that limits voltage drop to 3 %?
Exactly one answer is correct.
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Correct answer to question 13036
- D: 3 AWG
Explanation
Allowed drop is 0.03 x 208 = 6.24 V, and CM = 1.732 x 12.9 x 90 x 150 / 6.24 = 48,339 circular mils. 4 AWG (41,740) is too small and 3 AWG (52,620) is the first size that works; using the single-phase factor 2 would wrongly lead to 2 AWG.
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