Nec 314.28(a)(1)(2)(3)

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Jbox with 4" entry conduit containing (4) mult-conductor cables of 2AWG conductors, feeding four motors via (2) 2" conduits. Jbox is 20"W X 24"H. Art. 314.28(A)(1)(2) show the box as being too small to meet code. Another inspector suggests that using section (3) i.e. labeling the box with a permanent marking will solve the problem. I understand section (3) to mean that the boxes or conduit bodies are suppose to be factory labeled as opposed to labeled in the field.
I'd like some clarification on this code section.
 
Nec 314.28(a)(1)(2)(3)

20"W X 24"H X 6"D box. 4" entry conduit w/4-3c #2AWG multi- conductor cables feeding out to four 40HP motors via 2" conduits. Box seems too small to satisfy this article. 4" conduit six times rule cannot be met regarding paragraph three of section (2). Is this correct or is there a different interpretation?
 

augie47

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Unless I made a mistake, if it's an angle pull and the conduits and box are properly orientated, you should be o.k.

4" x 6 = 24
2" x 6 = 12 +2 +2 + 2 =18

straight pull = problem
 

Dennis Alwon

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Unless I made a mistake, if it's an angle pull and the conduits and box are properly orientated, you should be o.k.

4" x 6 = 24
2" x 6 = 12 +2 +2 + 2 =18

straight pull = problem

Well maybe I am wrong again. The bold part has me confused.

Angle or U Pulls, or Splices. Where splices or where angle or U pulls are made, the distance between each raceway entry inside the box and the opposite wall of the box shall not be less than six times the metric designator (trade size) of the largest raceway in a row. This distance shall be increased for additional entries by the amount of the sum of the diameters of all other raceway entries in the same row on the same wall of the box. Each row shall be calculated individually, and the single row that provides the maximum distance shall be used.
 

Dennis Alwon

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I must apologize. I have read this article 4 times and I cannot make heads or tails of what they are getting at. Wish I had the handbook. :)
 

Buck Parrish

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NC & IN
I must apologize. I have read this article 4 times and I cannot make heads or tails of what they are getting at. Wish I had the handbook. :)


Yep, your sure missing out.;)
The hand book has several nice illustrations on that topic. To late to bother getting the 08 . The 11 will be out soon.
 

Volta

Senior Member
Location
Columbus, Ohio
... The bold part has me confused.

Yep, your sure missing out.;)
The hand book has several nice illustrations on that topic. To late to bother getting the 08 . The 11 will be out soon.
But until then, you can trust Augie's quick demonstration.
Unless I made a mistake, if it's an angle pull and the conduits and box are properly orientated, you should be o.k.

4" x 6 = 24
2" x 6 = 12 +2 +2 + 2 =18

straight pull = problem

On the second line, he calculates the first 2" raceway x 6 to equal 12".
Then he is adding 2" for the second pipe, 2" for the third, and another 2" for the fourth.

Of course we don't know how the entries are actually run, but he showed that it is possible with this box.
 

mcclary's electrical

Senior Member
Location
VA
Jbox with 4" entry conduit containing (4) mult-conductor cables of 2AWG conductors, feeding four motors via (2) 2" conduits. Jbox is 20"W X 24"H. Art. 314.28(A)(1)(2) show the box as being too small to meet code. Another inspector suggests that using section (3) i.e. labeling the box with a permanent marking will solve the problem. I understand section (3) to mean that the boxes or conduit bodies are suppose to be factory labeled as opposed to labeled in the field.
I'd like some clarification on this code section.

Ther is nothing that requires a factory marking, since the box itslef could be homemade. But if I'm reading this correctly, Do you mean falsly mark the box with a number? I wouldn't agree to that, but if you're confident about your measurements, you could certainly mark the box with a SHarpie and meet code.

However, in YOUR PARTICULAR situation, (3) could only be used if the dimensions are LESS THAN thos required in (1) and (2).

Also, they need to derate according to 310.15 (b) (2) (a)
 

don_resqcapt19

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Illinois
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retired electrician
Ther is nothing that requires a factory marking, since the box itslef could be homemade. But if I'm reading this correctly, Do you mean falsly mark the box with a number? I wouldn't agree to that, but if you're confident about your measurements, you could certainly mark the box with a SHarpie and meet code.
...
The marking required by 314.28(A)(3) must be applied by the manufacturer of the box or conduit body and is part of the listing. It cannot be made up in the field.
 

mcclary's electrical

Senior Member
Location
VA
The marking required by 314.28(A)(3) must be applied by the manufacturer of the box or conduit body and is part of the listing. It cannot be made up in the field.

Yep, I missed the words "listed for"


But that wouldn't help him anyway. (3) would only apply if the dimensions are less than required in (1) and (2). Right?
 

Volta

Senior Member
Location
Columbus, Ohio
Jbox with 4" entry conduit containing (4) mult-conductor cables of 2AWG conductors, feeding four motors via (2) 2" conduits. Jbox is 20"W X 24"H. Art. 314.28(A)(1)(2) show the box as being too small to meet code. Another inspector suggests that using section (3) i.e. labeling the box with a permanent marking will solve the problem. I understand section (3) to mean that the boxes or conduit bodies are suppose to be factory labeled as opposed to labeled in the field.
I'd like some clarification on this code section.
I going to assume that this is the same box as mentioned in this thread.
Ther is nothing that requires a factory marking, since the box itslef could be homemade. But if I'm reading this correctly, Do you mean falsly mark the box with a number? I wouldn't agree to that, but if you're confident about your measurements, you could certainly mark the box with a SHarpie and meet code.

However, in YOUR PARTICULAR situation, (3) could only be used if the dimensions are LESS THAN thos required in (1) and (2).

Also, they need to derate according to 310.15 (b) (2) (a)

I agree that the box can be made it the field, if not in a wet location unless you get it listed 314.15. As the manufacturer, you would need to durably and legibly mark your name on it 314.44.

The cubic measurement is not relevant here, only the distance from entry to opposite, or to other entry. If the raceways were laid out properly, Augie showed that this box can work.

Good point with the derating in the 4".

The marking required by 314.28(A)(3) must be applied by the manufacturer of the box or conduit body and is part of the listing. It cannot be made up in the field.

True, via listing. But sub-section (A)(3) is only for boxes or bodies smaller than normally required for the entry size. This application need not necessarily include a box smaller than required by 314.28(A).
 
Well maybe I am wrong again. The bold part has me confused.

Each wall in the box shall be calculated individually, and the single row that provides the maximum distance shall be used.

If you have one wall with a 3" conduit entering the box, the calculation will be 3" x 6 if it is a angle or U pull. 3" x 8 if it is a straight pull. If there is any other conduit in that same wall, you have to add the size of it to the end of the calculation. So, if you have a 3", a 2", and another 2", in an angle pull, you calculate likewise. 3" x 6 = 18 + 2" + 2" = 22"
 

Dennis Alwon

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Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Each wall in the box shall be calculated individually, and the single row that provides the maximum distance shall be used.

If you have one wall with a 3" conduit entering the box, the calculation will be 3" x 6 if it is a angle or U pull. 3" x 8 if it is a straight pull. If there is any other conduit in that same wall, you have to add the size of it to the end of the calculation. So, if you have a 3", a 2", and another 2", in an angle pull, you calculate likewise. 3" x 6 = 18 + 2" + 2" = 22"
Thank you. Thats where my confusion was.
 
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