310.15(b)(1)(1) vs 310.15(b)(1)(2)

Ponchik

Senior Member
Location
CA
Occupation
Electronologist
Besides one is for 86F and one is 104F what is the difference between the two tables? 310.15(b)(1)(1) vs 310.15(b)(1)(2)?

I have always used the 86F table. When is the 104F table used?

TIA
 
Besides one is for 86F and one is 104F what is the difference between the two tables? 310.15(b)(1)(1) vs 310.15(b)(1)(2)?

I have always used the 86F table. When is the 104F table used?

TIA
104F table outdoor application, free air,
single insulated cables
The two tables give different final ampacities, So not mix up
 
Got it. Thanks you.

I had never noticed the note under each of the tables.
 
104F table outdoor application, free air,
single insulated cables
The two tables give different final ampacities, So not mix up
This is not correct.

T310.17 is for "single insulated conductors in free air" and would use the 86F Table.

T310.18 is for "not more than 3 conductors in raceway or cable", and would use the 104F table.
 
This is not correct.

T310.17 is for "single insulated conductors in free air" and would use the 86F Table.

T310.18 is for "not more than 3 conductors in raceway or cable", and would use the 104F table.
Correct, but my point if T310.17 used without 104F correction factor, final ampacity not same as when 104F table used directly (correction factor =1)
 
#1 THWN doesn't have an ampacity in T310.19.
Well, more clarity, this question:
Two outdoor installations. Both single insulated, same size cable in free air. But one ampacity on base 30C ambient and other 40C base ambient. Ampacity of each cable?
 
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