Conductors per phase

  • Thread starter Dwa
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  • #1
Dwa
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How do you determine the number of conductors per phase?

From my understand, the full load amperage divided by the desired wire size's ampacity rounded up if there is a remainder.

An example: If I have a 361 Full load Amp motor from the NEC table and I calculated the motor circuit conductor protection, which the specs of the motor 300 HP, 3 Phase, 60 Hz, 480V. 125 % x 361 Amps is 451 Amps. Which Amp would I chose to divide my desire wire? I would assume to use the 451 Amps for overload protection, but the calculations don't look right if I use 600MCM/kcmil wire.
 

Answers and Replies

  • #2
anorlunda
Staff Emeritus
Insights Author
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Wire sizing is often dictated by starting surges, not full load current
 

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