Does the ground count for fill?

[deharoj]

Hi -

I need to confirm if the engineer is correct. He asking me to put 3 #2/0 awg thhn in a 1-1/2" EMT conduit plus the # 6 awg ground wire. Annex C table C-1 allows for only 3 conductors, so does the ground count as a conductor for fill. Am I correct, the conduit is to small?

 

[iwire]

If the EGC is in the pipe it counts as fill.

But forget the tables when you have mixed sizes, you have to do the math.

 

[augie47]

The answer is yes and no.
Yes the ground does count in conductor fill, and
No the conduit is not too small.
If you do the actual calcualtions the fill is within limits.
The fact that the Tables show (3) simply means it will not take (4).

 

[charlie b]

I agree with Bob and with Gus. And I have done the math:
? Per table 4, a 1.5 inch EMT filled to 40% would have a fill area of 0.814 in2.
? Per table 5, a 2/0 THHN has an area of 0.2223 in2, so three of them would have an area of 0.6669 in2.
? Per table 5, a #6 THHN has an area of 0.0507 in2.
? That adds up to .7176 in2.
? Q.E.D.

 

[deharoj]

Thank you guys very much. It makes sense to do the math on conduit fill. I appreciate it a lot.