Raceway calculation

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bigpapa400lb

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A 120/208 volt, three phase 4-wire feeder is installed in a raceway in free air to supply a 24,000 VA, non continuous, electric discharge lighting load. This THW feeder will pass through an ambient temperature of 100 degrees F. What is the minimum allowable ampacity of this feeder?

My calculation 24000/360 = 67A x .88 x .80 = 47A
Answer key says 95A ?
 
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3-D

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Location
Washington State
Might help as a self check to remember that higher ambient temps and added wires in the raceway should require higher ampacity, not lower. If your math gives you a lower number, then, good time to stop and see if you multiplied when you should have divided, or subtracted when you should have added.

Hello all, I am new to this forum and have been quite impressed with what I've read so far.

Jim
 
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