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

[Sparky Bill PE]

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". 

 

[BebeshKing PE]

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". 

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. 

 

[Sparky Bill PE]

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. 

Thank you! I luckily got it right (doing that method) but I never noticed in table 16 that it says its based off 30 degrees! Thanks a ton!