clearance from stud face

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jimport

jimport

Senior Member
Location
Outside Baltimore Maryland
Occupation
Master Electrician
I am sure that I have seen a post regarding NM clearance from the stud face in regards to using the KO next to the stud not meeting the 1 1/4" dimension. This came up in on another forum but I must be using the wrong search criteria.

TIA,
 
To expand on this the person says they have gotten cited for using the KO in the plastic box as too close to the stud as it does not keep the required 1 1/4" distance.

Seems to me this may have talked about the clearance from the back of the box to the opposite side drywall too.
 
jimport said:
To expand on this the person says they have gotten cited for using the KO in the plastic box as too close to the stud as it does not keep the required 1 1/4" distance.

Seems to me this may have talked about the clearance from the back of the box to the opposite side drywall too.
Click to expand...


So then why would UL list a plastic box with KO's next to the stud if you can't use them?

I have never been dinged on this one:-?
 
2008 NEC
(D) Cables and Raceways Parallel to Framing Members and Furring Strips. In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed parallel to framing members, such as joists, rafters, or studs, or is installed parallel to furring strips, the cable or raceway shall be installed and supported so that the nearest outside surface of the cable or raceway is not less than 32 mm (11/4 in.) from the nearest edge of the framing member or furring strips where nails or screws are likely to penetrate. Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by nails or screws by a steel plate, sleeve, or equivalent at least 1.6 mm (1/16 in.) thick.
Click to expand...
The cable between the staple closest to the box and the box is NOT installed parallel to the framing. The cable is installed to deflect to whichever opening of the box it is entering.
 
macmikeman said:
I bet most field inspectors if they had such an issue would not see it that way. . .
Click to expand...
BoxEntry1.jpg
I entreat dialog. . .
 
No matter how you draw it or install it, there is a section, maybe a very very short section, at the KO that is parallel to the framing member...you can't use the KO next to the framing member unless you use a nail plate to protect the NM.
 
don_resqcapt19 said:
. . .there is a section, maybe a very very short section, at the KO that is parallel to the framing member...
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The problem with claiming that, is that "parallel" is the only distinction the NEC 300.4(D) requires. In a real installation my cable, entering the first KO, is going to be askew a little bit, to a lot. . . therefore, NOT parallel.

I will grant that there is "a very very short section" in the outer arc of the cable that is parallel, however.
 
480sparky said:
How can an arc (the cable) be parallel to a straight line (the stud)?
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The "parallel" bit, that is very, very short comes from a trick of calculus.

Approximate a real curve with a series of points along the curve, where the points are all the same distance d apart. Connect the points with straight lines. Now, add more points, reducing the distance d so that it "approaches" zero. The approximate curve becomes more and more like an actual curve.

Calculus teaches us that the adding of more points, an ever smaller d apart, can go on forever, and that the very, very short bits become the curve, while there are still very, very short straight bits there.
 
al hildenbrand said:
The "parallel" bit, that is very, very short comes from a trick of calculus.

Approximate a real curve with a series of points along the curve, where the points are all the same distance d apart. Connect the points with straight lines. Now, add more points, reducing the distance d so that it "approaches" zero. The approximate curve becomes more and more like an actual curve.

Calculus teaches us that the adding of more points, an ever smaller d apart, can go on forever, and that the very, very short bits become the curve, while there are still very, very short straight bits there.
Click to expand...

I don't think fractal geometry is something an inspector is going to understand.
 
480sparky said:
I don't think fractal geometry is something an inspector is going to understand.
Click to expand...
:smile:

Don,

This is what I mean by askew. The photo prop is un-retouched, I merely turned it so the camera lens would allow the dimension missing in the first photo.


AskewEntry.jpg
 
I just think the intent of the CMP's when this section was put in the NEC was that a person driving a nail into the stud (no what ifs) were to have deflected the nail on a knot or another nail, it could shoot out the side of the stud and hit a wire stapled to the stud, where a cable is of a distance from the stud lets say even a half inch this type of nail penetration would not happen, I don't think it was the CMP's intent to include the "what ifs" of a un professional carpenter/dry waller to miss the stud as a whole, we know it happens in the real world but IMO this is a "what if" I also think this is why we see only 1.5" wide nail plates, they were made with the same intent in mind.
 
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