Generator Breaker Sizing

[kbrannon]

I work for an OEM and we are adding breakers to generators. The breakers are mounted inside of cabinets that are fully vented and are only energized when the generator is running. All of the cooling air for the generators runs through the cabinets. Can someone point me to where this would be considered "free air" in the code book?

 

[Dennis Alwon]

I think the only thing you would find is that tables 310.15(B)(16) show either in ducts, raceways cable or free air so I guess that is the closest- (free air)

 

[DrSparks]

The National Electric Code does not govern equipment manufacturing.

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[Jamesco]

I work for an OEM and we are adding breakers to generators. The breakers are mounted inside of cabinets that are fully vented and are only energized when the generator is running. All of the cooling air for the generators runs through the cabinets. Can someone point me to where this would be considered "free air" in the code book?

What's the reason for adding the breaker?
Just a guess to protect the generator from being overloaded from a continuous connected load or a Line to Line or Line to neutral low resistance fault event.

I would size the breaker at 80% of the rated FLA of the generator. Check your competition, do the math, you will find that's what they are doing.