Services & DistributionQuestion 45 of 521
What is the full-load secondary current of a 45 kVA, 3-phase, 208 V transformer?
a.216 A
b.125 A
c.108 A
d.94 A
Explanation
I = 45,000 / (1.732 x 208) = 125 A. The formula uses line-to-line voltage times the square root of 3; the other values drop the sqrt-3 factor or use single-phase math.
Law Reference: 2023 NEC §450.3Practice all 521 questions free — no signup required.
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