fastening multiple NM cables

[dlarson]

This is without a doubt the most interesting site I've come across. I'm in my forties and have wondered about the electronics instead of electricity career choice made so many years ago; ever since I added lights to my bedroom when I was 13 (never heard of NEC at that point, but I've read some portions out of necessity since then).
I was reading the forum thread about fastening/clamping NM cable to an NM box. I'm wondering two things:
1) There was a code quote that said it wasn't necessary to clamp in the NM box if it was single gang and stapled within 8". Is that to say that any box bigger than that needs internal clamping?
2) Can you stack NM cables under one staple? If so, does it still satisfy the clamp requirement?
(Do they make the staple nails long for a reason?)

Thanks!

 

[sparkmantoo]

Re: fastening multiple NM cables

off the top of my head without the book here, i would say that anything larger than a single gang box you are required to internally clamp the nm cable and staple it. i know the blue carlon boxes have those wedges that like to break off and the bakelite boxes have metal clamps that fall out. make sure you use them. in our area they allow you no more than two TWO wire cables, of the same size, under one staple as long as it is listed for that purpose. one three wire per staple. no combinations of two and three wire. you can use what we call christmas trees which allow you to strap multiple cables inside a stud and also maintains your clearance from the face of the stud. i am sure there are other opinions out there as to how to do it, this is what they allow here.

 

[dlarson]

Re: fastening multiple NM cables

Thanks for the response. Can I assume then that it's OK to make wire runs using the same stacking rule, as long as I fasten every 4&1/2 feet? I'm such a putz, I'm usually in the 3 to 3&1/2 foot neighborhood anyway...

Did I mention this was a great forum?
It makes me feel better when there are others, even learned electricians, who can't decipher the codebook single-handed.

 

[wayne123]

Re: fastening multiple NM cables

We are allowed to use tie wraps to secure romex to already stapled romex.This makes for a neat apearance an saves time and money since you don,t have to buy christmas trees.

 

[sparkmantoo]

Re: fastening multiple NM cables

good idea wayne never thought of that. see i guess it does pay to find out if there is more than one way to skin that cat.

 

[pierre]

Re: fastening multiple NM cables

Wayne

Section 300.11(C) Cables Not Used as Means of Support. Cable wiring methods shall not be used as a means of support for other cables, raceways, or nonelectrical equipment. (2002 NEC)

Tywrapping one NM cable to another for support is not permitted as far as code is concerned.
One of the reasons is bundling reduces the heat dissipating capabilities and can cause degradation of the conductor insulation.

Pierre

 

[sparkmantoo]

Re: fastening multiple NM cables

i don't consider that supporting though. i consider that securing. supporting in my opinion is to hang something from an object. when you staple a wire to a stud you do not support it you secure it. you can drive a nail in the stud and secure your wire with a tie wrap. just a difference of opinions.