Question when to use 30 degrees Celsius table Ampacity vs 40 degrees.

SparkyBill said:

I never know when to use the temperature correction table 310.15(B)(2)(a) or 310.15(B)(2)(b) 

I don't see in the question where it says it's "based on 30 degrees or 40 degrees Celsius". 

Click to expand...

BebeshKing said:

The question says that the conductor is insulated, temperature rating of 75 degrees, routed in a raceway, and connected to a 480V load. That being said, you will need to use Table 310.15(B)(16). And that table is specifically based on Ambient Temperature of 30 Degree Celsius. 

Click to expand...