Article 376.22 Cross Section

[Newtechemmanuel]

I am an instructor at the local community college and I teach in the electrical systems technology program. I've been doing this for about 5 years and have trained over 2,000 students. I had a student come to me yesterday with a question about Article 376 Metal Wireways. His question was about Article 376.22 (A): The sum of the cross-sectional areas of all contained conductors and cables at any cross section of a wireway shall not exceed 20% of the the interior cross-sectional area of the wireway.

What I do not understand is what cross-sectional area are they using and how are they finding it? Are they referring to Table 8 in chapter 9 to find the Overall area of each conductor and summing those and dividing by 20% or are they using Table 5 chapter 9 to find the Appox area and the summing those up and dividing by 20% or are they opening the wireway and looking inside and at any point where a wire literally cross another wire the 20% applies.

I found a link on https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=298.1

and they have a picture of an open wireway and in the wireway they have a yellow box with words cross section but I'm seeing a lot of places where conductors are crossing within the wire way.

 

[Newtechemmanuel]

I am an instructor at the local community college and I teach in the electrical systems technology program. I've been doing this for about 5 years and have trained over 2,000 students. I had a student come to me yesterday with a question about Article 376 Metal Wireways. His question was about Article 376.22 (A): The sum of the cross-sectional areas of all contained conductors and cables at any cross section of a wireway shall not exceed 20% of the the interior cross-sectional area of the wireway.

What I do not understand is what cross-sectional area are they using and how are they finding it? Are they referring to Table 8 in chapter 9 to find the Overall area of each conductor and summing those and dividing by 20% or are they using Table 5 chapter 9 to find the Appox area and the summing those up and dividing by 20% or are they opening the wireway and looking inside and at any point where a wire literally cross another wire the 20% applies.

I found a link on https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=298.1

and they have a picture of an open wireway and in the wireway they have a yellow box with words cross section but I'm seeing a lot of places where conductors are crossing within the wire way.

Furthermore I found and Articler

I am an instructor at the local community college and I teach in the electrical systems technology program. I've been doing this for about 5 years and have trained over 2,000 students. I had a student come to me yesterday with a question about Article 376 Metal Wireways. His question was about Article 376.22 (A): The sum of the cross-sectional areas of all contained conductors and cables at any cross section of a wireway shall not exceed 20% of the the interior cross-sectional area of the wireway.

What I do not understand is what cross-sectional area are they using and how are they finding it? Are they referring to Table 8 in chapter 9 to find the Overall area of each conductor and summing those and dividing by 20% or are they using Table 5 chapter 9 to find the Appox area and the summing those up and dividing by 20% or are they opening the wireway and looking inside and at any point where a wire literally cross another wire the 20% applies.

I found a link on https://www.electricallicenserenewal.com/Electrical-Continuing-Education-Courses/NEC-Content.php?sectionID=298.1

and they have a picture of an open wireway and in the wireway they have a yellow box with words cross section but I'm seeing a lot of places where conductors are crossing within the wire way.

Furthermore, I found an old thread: His question was

Need to calculate the size trough needed for 16-500kcmil (line and load from ATS) 10 foot distance.
376.22 tells me that the sum of the cross sectional area of all contained conductors at any cross section of a wireway shall not exceed 20% of the interior cross-sectional area of the wireway.
My calculations for 16- 500kcmil (.7073 x 16) = 11.30 total if I divide that by 20% I come up with a cross sectional area of 56.60
How do I calculate the cross section of the trough size I would need?

Where .7073 come from I looked all over my NEC code book I even have one from 2005 that of which that thread had been posted and I can't find .7073 in any of the tables>

 

[david luchini]

Where .7073 come from I looked all over my NEC code book I even have one from 2005 that of which that thread had been posted and I can't find .7073 in any of the tables>

Chapter 9, Table 5.... 0.7073 square inches is the area of a 500mcm THHN, THWN or THWN-2 conductor.

 

[Newtechemmanuel]

Chapter 9, Table 5.... 0.7073 square inches is the area of a 500mcm THHN, THWN or THWN-2 conductor.

Thanks a ton. You've just confirmed what the old StallCups said, I am not sure how come I couldn't interpret this article. I am normally good at this.

 

[drktmplr12]

Thanks a ton. You've just confirmed what the old StallCups said, I am not sure how come I couldn't interpret this article. I am normally good at this.

we are all imposters until we aren't.

you are here trying to learn-good on you!