NM wiring methods

[mivey]

Better yet show him Article 314.17(C) Exception (Last line of) "Multiple cable entries shall be permitted in a single cable knockout opening"

see post #14

 

[S'mise]

Huh?

Huh?

Single gang box is ok if secured within 8" of box, not for multi gang.

Hate those Carlon boxes.

Care to explain this?

Multi-gang Carlon boxes do not have internal clamps either.


314.17(C) ex says "single entry" not single gang

 

[e57]

Care to explain this?

Multi-gang Carlon boxes do not have internal clamps either.

Some do - some don't. The ones on this do... (Most do...)

Anyway - the manufacturer addresses this question, and inadvertently answers the OP's here.

How many cables can you put in one integral cable clamp?

One. The National Electrical Code section 314.17(c) Exception allows you to put multiple cables through a knockout, but only one is allowed through each clamp.​

Ref: http://www.carlon.com/FAQs/FAQ-ZipBoxes.pdf

The openings here are all clamps...

 

[jimport]

S'mise

The multigang boxes actually have a clamp built into the box to hold one cable, not multiple cables. A single gang box just has a KO for the cable entry.

 

[e57]

These are just knock-outs... And allow multiple cables if supported correctly to make use of the exception.

 

[macmikeman]

Switch brands.

 

[al hildenbrand]

314.17(C) ex says "single entry" not single gang

Gotta read the whole Exception. The last sentence does not stand alone.

2008 NEC
314.17(C) Exception: Where nonmetallic-sheathed cable or multiconductor Type UF cable is used with single gang boxes not larger than a nominal size 57 mm ? 100 mm (21/4 in. ? 4 in.) mounted in walls or ceilings, and where the cable is fastened within 200 mm (8 in.) of the box measured along the sheath and where the sheath extends through a cable knockout not less than 6 mm (1/4 in.), securing the cable to the box shall not be required. Multiple cable entries shall be permitted in a single cable knockout opening.

 

[S'mise]

Ahhhh!

Ahhhh!

Thanks for explaining this guys. I've always stapled within 8" with a plastic box regardless. I had not realized that the plastic tabs are considered a clamp.

I love it when I learn something!

 

[LarryFine]

I've always stapled within 8" with a plastic box regardless. I had not realized that the plastic tabs are considered a clamp.

Yep. The clamps in multi-gang boxes work well with stackers, which don't grip.

You also don't have to staple cables run through horizontal holes and enter boxes if they're close enough.

 

[millieamp]

Thanks for the support, people. I emailed carlon and they didn't reply (yet?). My handbook is the '05 edition and Exhibit 314.5 is about a flexible surface extension from a flush-mounted box.

If the issue is securing the cables tightly, then the 8" staple rule would seem to apply, but what do I know? If the issue is tearing the insulation, I could see it as a concern but I really do need to hear from Carlon (Lamson and Sessions).

But, what the hell, I ended up redoing the work. Sometimes you just have to bend over and take it.

 

[mvannevel]

You also don't have to staple cables run through horizontal holes and enter boxes if they're close enough.

That was true through the '99 Code cycle. Beginning with the '02 cycle NM through holes or notches is considered "secured and supported" where the holes and notches do not exceed 4 1/2 feet AND the cable is SECURED IN PLACE BY AN APPROVED MEANS within 12" of every box. So, if your AHJ says being run through a hole is secured you're good. Otherwise, you'll need some other means to secure it that is suitable to the AHJ.

As to the O.P.'s question, I've always allowed that. But, the bottom line is what the listing, labeling and manufacturers instructions for the Carlon box says. The U.L. White Book, under the category QCMZ for nonmetallic outlet boxes, says that when clamps are provided, they have been tested for securing only cable per clamp. For single gang boxes, it is intended that one or more NM cables enter through a single or multiple stage knock-out. So, in this instance, 110.3(B) applies, and you are installing and using the box in accordance with it's listing and labeling.

But, what the hell, I ended up redoing the work. Sometimes you just have to bend over and take it.

No, you shouldn't have to bend over and take it. A polite discussion with the inspector pointing out this listing in the White Book should solve the problem. The idea that you "just have to bend over and take it" is what makes our job as inspectors and your job as electricians difficult. An open dialogue between both parties is the best way to resolve an issue like this.

 

[al hildenbrand]

My handbook is the '05 edition and Exhibit 314.5 is about a flexible surface extension from a flush-mounted box.

Ya, the 2008 Handbook Exhibit 314.5 is new (it wasn't in the '05). The '08 Exhibit 314.5 shows an 18 cubic inch blue nail-on single gang wall box (Carlon B118A) that has the square knockouts, and two NM-B cables go thru one knockout.

Thanks for the support, people. I emailed Carlon and they didn't reply (yet?). . . If the issue is securing the cables tightly, then the 8" staple rule would seem to apply, but what do I know? If the issue is tearing the insulation, I could see it as a concern but I really do need to hear from Carlon (Lamson and Sessions).

Perhaps you missed the links in E57's Post #23.

This Carlon FAQ in particular has at least three Q&As that, to me, seem to answer your question.

Also, note in this link on page two the correct, Carlon illustrated, technique for using the internal box clamps of the blue boxes. No tool is used to pry open the clamp, just the cable.

My experience with the blue box clamps is that they are easily damaged by being bent too far, and therefore, no longer grip as a clamp.

 

[lightitup]

As an interesting side note - 08 Exhibit 314.5 - I have been called out by inspectors for using the first knock out on 2X4 frameing. Two wires in one knock out was OK but needed to use the knock out farthest away from stud.
The 1 1/4" rule for protection from rock screws.

 

[chris1971]

An inspector told me that it's a code violation to put the NM cable in the opening closest to the stud of a single gang nail on box. Why?

 

[shepelec]

An inspector told me that it's a code violation to put the NM cable in the opening closest to the stud of a single gang nail on box. Why?

Must be in the "My town code book".

 

[lightitup]

An inspector told me that it's a code violation to put the NM cable in the opening closest to the stud of a single gang nail on box. Why?
Today 10:01 AM

300.4(d) 1 1/4" from face of stud.

 

[e57]

An inspector told me that it's a code violation to put the NM cable in the opening closest to the stud of a single gang nail on box. Why?

As an interesting side note - 08 Exhibit 314.5 - I have been called out by inspectors for using the first knock out on 2X4 frameing. Two wires in one knock out was OK but needed to use the knock out farthest away from stud.
The 1 1/4" rule for protection from rock screws.

300.4(d) 1 1/4" from face of stud.

That is really reaching for a violation IMO - While it is by the wording - If I remember correctly that code section contains the word "likely" and IMO the likelihood is low.... While many of us think rockers are not fit to breath air - the chances of a shiner screw or nail at the average hieght of a receptical is low - since said 'shiner' would need to be a full inch plus off and at just the right hieght.

 

[al hildenbrand]

As an interesting side note - 08 Exhibit 314.5 - I have been called out by inspectors for using the first knock out on 2X4 frameing. Two wires in one knock out was OK but needed to use the knock out farthest away from stud.
The 1 1/4" rule for protection from rock screws.

Yeah. I've had that too, here in the Twin Cities.

But it is not consistant, and I believe it is an error.

See my explanation in this thread that I started on the issue.

 

[electricmanscott]

Good lord we've gone mad. :roll:

 

[al hildenbrand]

Lightitup,

I did the work in that thread before the 2008 NEC Handbook was out. Had I had that photo in the '08 NECH Exhibit 314.5 I could have further confronted the Inspector.