Motor Feed calculations

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kgk1961

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PerNEC 430.250 a 100HP Induction type motor has a FLA of 124A. This requires #2/0 AWG THWN.
Thenameplate rating is only 109A. This requires #1/0 AWG THWN. (Yes, I did calculate this via the code requirements.)

Which takes precedence when sizing feeder conductors?

Please note: This is a speciality motor that cannot, and will not, ever be replaced by a "shelf" motor. If this motor ever fails, it will be rebuilt, or a new motor will be ordered from the original pump manufacturer.
 
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Unless the motor falls under one of the exceptions in 430.6, and it does not appear to, you will need to use the Table value
 
kgk1961 said:
PerNEC 430.250 a 100HP Induction type motor has a FLA of 124A. This requires #2/0 AWG THWN.
Thenameplate rating is only 109A. This requires #1/0 AWG THWN. (Yes, I did calculate this via the code requirements.)

Which takes precedence when sizing feeder conductors?

Please note: This is a speciality motor that cannot, and will not, ever be replaced by a "shelf" motor. If this motor ever fails, it will be rebuilt, or a new motor will be ordered from the original pump manufacturer.
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The tables take into consideration the worst case efficiency or power factor at the horsepower values given.

You are likely to not even find a new 100 hp motor that has a FLA of 124 amps marked on it, but NEC wants to make sure a circuit designed for a 100 hp motor can handle any 100 hp motor that may be connected to it.
 
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