310.16 Question...

[1793]

I have a job upcoming that will involve some underground PVC work. It has been a very long past two weeks and I feel rather "brain dead" and I need some input.

I'm running a 100A feed out to a separate structure where I'll have a 100A 20 circuit MB panel. My question is in regards to the size of the conductor needed to feed this panel. Do I need to adjust for this run being underground, I would like to pull a #3 THWN and protect it by a 100A breaker in the Main panel. According to 310.16 #3 CU is good for 100A @75 deg. but, only 85A @60 deg.

Do I have to lower the ampacity from 75 to 60 due to being underground, a wet location?

Thanks

 

[raider1]

What type of conductors are you using?

Chris

 

[NolaTigaBait]

Use thwn and you can use the 75 chart.

 

[1793]

what type of conductors are you using?

Chris

thwn cu........

 

[A/A Fuel GTX]

You are good to go with #3's unless you have voltage drop issues, assuming 3 CCC's.

 

[1793]

You are good to go with #3's unless you have voltage drop issues, assuming 3 CCC's.

No voltage drop on this one.

Thanks for the help today, from everyone. I thought I was OK but started doubting myself after the last few days.