75 degree ampacity of 310. 15(B)(16) and 240.4 (B) and 110.14 (C)

[transman2]

If I install a feeder for a sub panel with 500 AWG THHN wire (380 amps) using the 75 C allowable ampacities chart on 310.15(B)(16) and due to the fact that the breaker manufacture termination lugs are only rated at 75 degrees and following 110.14 (C),(a)(b). However 240.4 (B) says I am permitted to go the next higher standard overcurrent device rating which would be 400 amps. Is this a conflict?? Not sure how to rule on this and hope I can get some help. Thanks!!

 

[infinity]

500 kcmil copper THHN is rated for 380 amps @ 75° C as you've stated. As long as the calculated load is 380 amps or less you can use the next size up rule to get to the next standard size of 400 amps.

 

[Smart $]

500 kcmil copper THHN is rated for 380 amps @ 75° C as you've stated. As long as the calculated load is 380 amps or less you can use the next size up rule to get to the next standard size of 400 amps.

FIFY

 

[Smart $]

We also get lazy and forget to state the conductor ampacity cannot be greater than the 75°C column value or the adjusted and corrected ampacity, whichever is the lesser of the two.

 

[infinity]

I used the word connected just for you.

 

[GoldDigger]

I used the word connected just for you.

Did you use the word "lost" instead of "load" just for him too?

Sent from my XT1585 using Tapatalk

 

[infinity]

Did you use the word "lost" instead of "load" just for him too?

Sent from my XT1585 using Tapatalk

No that one is for you.

I've made the corrections, thanks.