Derating (8) #12 In a Conduit

Status
Not open for further replies.

DAL

Member
Can you have (8) #12 THHN wires in a conduit. I have (3) 20 A. 208 V.
I-P circuits & (1) 20 A. 120 V., all on 20 A. breakers, which equils (8) wires.
My though is #12 is raited at 25 A., so 25 X 70%= 17.5 A.

The inspector says I need #10, because he dosen't know the load.I told him it wasn't a continuous load. I tried to make the case that the circuits are on 20 A. breakers and that 20 X 80% = 16 A. which is less than 17.5 A.
The inspector said he needed something more to hang his hat on.
 

ryan_618

Senior Member
If he doesn't know the load, how does he know the breaker is the right size?

By the way, assuming you are using THHN, your 12 AWG condcutor is good for 30A, not 25A.

30A * 70% = 21A. Compliant installation, unless the load exceeds 20A at 100% of the noncontinuos load + 125% of the continuous.

210.19, 210.20, 310.15(B)(2)(a).
 
Status
Not open for further replies.
Top