clearance from stud face

[dcspector]

I don't think fractal geometry is something an inspector is going to understand.

Well Ken "thank you very little"....how do you spell that?......rectal geometry or sumpin like that? My dumb you said fractal......sorry.:grin:

 

[dcspector]

I start the requirment as Al displayed from first staple. Out here don't see staples anymore just Stackers and CJ's.

 

[al hildenbrand]

. . . just Stackers and CJ's.

"CJ" is a new one on me. What does it stand for?

 

[480sparky]

"CJ" is a new one on me. What does it stand for?

"Colorado Jim", after the inventor.

 

[al hildenbrand]

Thanks, Ken.

Now, back to my entreating dialog on 300.4(D).

All of you who require a nailplate over the first entry of a wall case when NM is installed . . . . Consider this detail image from the 2008 National Electrical Code Handbook 300.4(D) Exhibit 300.2 :

Even though the NM is strapped on the FACE OF A FRAMING MEMBER, almost directly against the ceiling surface material, there is no nailplate. . . . the ceiling surface material (acoustic tile, drywall, etc.) is LIKELY to be fastened to the furring strips. The cable is installed PARALLEL to the furring.

 

[electricmanscott]

Just to be clear, Is the discussion here that a nailplate is required to protect a peice of NM cable entering a box as shown in the picture in post #13? :-?

 

[infinity]

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.

I agree with Don. If you were to follow the actually wording of the code you would need a protective plate at each plastic box using a KO less than 1.25" from the stud. Seems pretty ridiculous to me. Maybe a proposal is in order. :smile:

 

[al hildenbrand]

I agree with Don.

So, Rob, how do you tell me that this last 8" of NM is installed parallel to the stud?

 

[infinity]

So, Rob, how do you tell me that this last 8" of NM is installed parallel to the stud?

IMO the part where the battery is is parallel to the stud.

 

[al hildenbrand]

IMO the part where the battery is is parallel to the stud.

There is no trick of the lens in this photo.

The battery is performing only a visual size reference. If I remove it, the cable remains approximately 15 degrees off parallel, having not been forced parallel by something like the shoulder of a conduit connector against a metal box.

Once inside the box, the cable ends and conductors commence.

 

[infinity]

There is no trick of the lens in this photo.

The battery is performing only a visual size reference. If I remove it, the cable remains approximately 15 degrees off parallel, having not been forced parallel by something like the shoulder of a conduit connector against a metal box.

Once inside the box, the cable ends and conductors commence.

It's just my opinion but trying to make a point based solely literal meaning of the word parallel is not going to satisfy the intent of the NEC. If I fold a V in the NM and staple it 1/2" from the stud face within the V can I say that 300.4 does not apply because the cable in and out of the V is not parallel to the stud?

 

[jeremysterling]

I agree with Don.

I agree with Al. Just because the NM between the last staple and the device box is installed perpendicular to the box entrance does not prove it to be parallel to the framing member.

The calculus explanation notwithstanding, perhaps more clarity from the code is warranted.

 

[al hildenbrand]

If I fold a V in the NM and staple it 1/2" from the stud face within the V can I say that 300.4 does not apply because the cable in and out of the V is not parallel to the stud?

I have no trouble seeing the bottom of the "V" under the staple, being for a "very, very short bit" parallel to the plane of the stud even as a trick of calculus.

My question, for you, however, is, how many degrees off parallel does the "intent of the CMP" say is still "parallel"?

And, while we are guided by the comments and other written record of the CMP, are we not still restricted only to the legally binding document in effect in various jurisdictions. . . the NEC alone?

Parallel simply means parallel. . . not parallel +/- 15 degrees.

 

[Sierrasparky]

IMO the part where the battery is is parallel to the stud.

Next well see composite boxes with metal backs because a stray nail /screw may peirce the box.
I've seen this happen.. I have also seen 8 10d nails in the back of a wall heater. Customer calls says wall heater smoking and fan not turning!!! OOPS!

 

[infinity]

I have no trouble seeing the bottom of the "V" under the staple, being for a "very, very short bit" parallel to the plane of the stud even as a trick of calculus.

My question, for you, however, is, how many degrees off parallel does the "intent of the CMP" say is still "parallel"?

And, while we are guided by the comments and other written record of the CMP, are we not still restricted only to the legally binding document in effect in various jurisdictions. . . the NEC alone?

Parallel simply means parallel. . . not parallel +/- 15 degrees.

Theoretically there is no such thing as parallel. Once you measure to a precise distance apart at two points, the infinite nature of mathematics will always allow you to measure even smaller. In a practical sense we can say two things are parallel but theoretically they never can be. :roll:

 

[480sparky]

Theoretically there is no such thing as parallel. Once you measure to a precise distance apart at two points, the infinite nature of mathematics will always allow you to measure even smaller. In a practical sense we can say two things are parallel but theoretically they never can be. :roll:

Fractal geometry!

 

[wwhitney]

Theoretically there is no such thing as parallel. Once you measure to a precise distance apart at two points, the infinite nature of mathematics will always allow you to measure even smaller. In a practical sense we can say two things are parallel but theoretically they never can be. :roll:

Don't forget the intermediate value theorem: If the stud line and the romex curve are in one plane, and at some point the romex is angled to one side of being parallel, and at another point the romex is angled to the other side of being parallel, there has to be point in between where it is exactly parallel. :smile:

Cheers, Wayne

 

[480sparky]

All this math stuff is a moot point anyway.

Space is curved, and there is no such thing as a straight line except in the realm of mathematics. Hence, there is no such thing as two parallel lines.

 

[electricmanscott]

Next well see composite boxes with metal backs because a stray nail /screw may peirce the box.
I've seen this happen.. !

This is exactly the reason I don't beleive this section is supposed to be interpreted this way. If it were, some manufacturer would surely be making their boxes with a nailplate extending from the back covering the area where the cables enter and beyond.

 

[al hildenbrand]

Theoretically there is no such thing as parallel.

OK, so when we are not at the theoretical job, but rather the real world job, how do we determine the number of degrees, +/-, off of a point on a straight plane ( the 3.5" wide stud face) that is "parallel" to the plane?

I maintain that, in my photo in this post, that the cable between the staple and the box is getting progressively farther away from the plane of the stud face. The photo represents, arguably, the common "as built" assembly of romex-to-a-wall case on a stud. The cable forms a simple ramp, a wedge, that does not level off and that goes into the opening on the wall case at an angle. Absolutely nothing about the common wall case is going to reliably force the cable to enter the wall case in a plane parallel to 3.5" stud face.

When the cable emerges from under the staple, it is more than 1.25" from the edge of the stud. When the cable crosses that 1.25" boundary it is only forming a ramp of some number of degrees away from the 3.5" wide plane of the stud.

The cable cannot enter the wall case unless the cable deflects away from the plane of the stud.

The cable has to be installed NOT parallel to the stud in order to enter the wall case.

Rob and Don, you state that this cable is "parallel" when it is obviously at an angle of some number of degrees to the plane it is "parallel" to. What document determines the +/- degrees off parallel that is still "parallel" at the "intent" of the CMPs?