Derating underground conductors

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Injun22-250

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Taking code class ths spring and came across a problem I hope you guys can help me with. If I bury a cable underground, and less than 10' is exposed, can I get more than the derating factor of 1 since it is buried underground and the earth has cooler ambient temperature? Also if so, where would this be in the code one way or the other?
 
310.16 is where you will find the correction factors for ambient. You don't gain much for cooler ambients - you just lose a lot for hotter. Since heat is the enemy here, that makes sense.
 
Earth may have a cooler temperature, but it is not as good a conductor of heat than is open air. The idea is to get the heat (i.e., as generated by current passing through the conductor) away from the insulation system.

If anything, going underground should reduce ampacity, not increase it.
 
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