Generator Inlet

[resistance]

I installed a 30A generator power inlet today?using 10-3NM-b. And the inspector told me the cable was too small. Hun???? I asked him how he figures. He said the cable should be sized larger to account for in-rush current. Hun??? Can someone tell me where he?s right. Note: The conversation between us was pleasant, but he clearly is off base. He passed it, but I?m lost on why he even talked about it???

 

[resistance]

??????

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[infinity]

You're not lost he's lost. If inrush current were a factor you would use a larger OCPD not a larger condcutor, same as you would for a motor circuit.

 

[resistance]

You're not lost he's lost. If inrush current were a factor you would use a larger OCPD not a larger condcutor, same as you would for a motor circuit.

Exactly!! He must have had too much Starbucks!!! :lol: Thanks for writing back. I appreciate when people respond to my post:thumbsup:.

 

[ron]

You just need to protect the conductors, so 30A breaker goes with a #10 wire.

 

[weressl]

I installed a 30A generator power inlet today?using 10-3NM-b. And the inspector told me the cable was too small. Hun???? I asked him how he figures. He said the cable should be sized larger to account for in-rush current. Hun??? Can someone tell me where he?s right. Note: The conversation between us was pleasant, but he clearly is off base. He passed it, but I?m lost on why he even talked about it???

310.15 Ampacities for Conductors Rated 0?2000 Volts.
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(3) Temperature Limitation of Conductors.​

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No conductorshall be used in such a manner that its operating temperatureexceeds that designated for the type of insulatedconductor involved. In no case shall conductors be associatedtogether in such a way, with respect to type of circuit,the wiring method employed, or the number of conductors,that the limiting temperature of any conductor is exceeded.​

Informational Note No. 1: The temperature rating of aconductor [see Table 310.104(A) and Table 310.104(C)] isthe maximum temperature, at any location along its length,that the conductor can withstand over a prolonged timeperiod without serious degradation. The allowable ampacitytables, the ampacity tables of Article 310 and the ampacitytables of Informative Annex B, the ambient temperaturecorrection factors in 310.15(B)(2), and the notes to thetables provide guidance for coordinating conductor sizes,types, allowable ampacities, ampacities, ambient temperatures,and number of associated conductors. The principal​

determinants of operating temperature are as follows:

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Clearly the ampacity tables ARE defined for the continuous current the conductor is expeceted to carry.

However, if there is a motor load that is close to ~1/3 of the generators rating and the conductor lenght is considerable, oversizing the conductors may allow a motor load to accelerate quicker and with more torque by reducing the voltage drop during inrush. Under adverse conditions, the generator(regulator) can stall out. Would need a lot more data, including the motor and generator capacities, impedances among others to even make an educated guess if this MAY be a problem.