310.16...again

[phono84]

it's been a while since ive de-rated for conduit fill so my question is, how many 3 hot/1 neutral groups can i put in a 3/4'' pipe if the wire is #12 thhn, and on a 20 amp ckt and the terminal ratings are unknown. i am confused if it is 30a X 70%=21a or if i have to base it off of the 75 degree column. anyway i would like to put 9 #12 hots with 3 neutrals in a 3/4'' on a 20 amp ckt.

 

[infinity]

First you need to determine if the neutrals are considered current carrying conductors based on 310.15(B)(4). If they're not your 9 circuits will have 9 CCC's. Next you'll need to determine the ampacity of the conductors based on their insulation and derate from there.

 

[LarryFine]

Phono, welcome to the forum!

i am confused if it is 30a X 70%=21a or if i have to base it off of the 75 degree column.

The former.

anyway i would like to put 9 #12 hots with 3 neutrals in a 3/4'' on a 20 amp ckt.

Perfectly okay.