Tables 310.15(B)(2)

[MasterTheNEC]

Again I know that, but when do they conditions match 40C. Can you give an example of when you use 40C

When you use tables other than 310.15(B)(16) and (17)...as i.e Tables 310.15(B)(18), (19), (20, and (21) along with Tables 310.60(C)(4), (C)(67), (C)(68), (C)(69)....and so on.

 

[Carultch]

When you use tables other than 310.15(B)(16) and (17)...as i.e Tables 310.15(B)(18), (19), (20, and (21) along with Tables 310.60(C)(4), (C)(67), (C)(68), (C)(69)....and so on.

When you use wire types / conditions that are laboratory tested at an ambient of 40C, instead of the more common 30C.

Type Z
Nickel-plated
Medium voltage
Concrete-encased conditions of installation

And all sorts of other less-common applications.