Bundling of Romex (NM cable)

[Roger Frazee]

Having participated in many arguments over the years on what constitutes a group of nm cables being bundled always led to the same conclusion ... that the NEC does not define it.

But it actually does provide a definition .. though in a rather odd place. It just took me a while after reading the previous thread on bunching romex to locate it.

Take a look at 520.2 Definitions .. this was in the 1999 NEC I had handy but I don't think it has changed.

Bundled. Cables or conductors that are physically tied, wrapped, taped, or otherwise periodically tied together.

Any comments ... ? The definition is part of the articles scope but none the less bundled is bundled I would think.

The term is used in 520-53 h2 and h3 and h4.

[Jim Port]

That is similar to how I would consider bundling. However, this cannot be enforced in a non Article 520 application.

I would also note that in the 08 Article 334.80 the derating note conditions are spelled out only apply where draft stopping or thermal insulation are in contact with the cable.

Also Article 392.11 has a section about cables laid in a single layer that gives a spacing requirement. Article 392.11(A)(1) seems to avoid the need to consider derating when cables are run in the Arlington raceway that was posted in the other thread. It is only concerned with the number of CCC in the cable, not the raceway.

[Bill Kriegh]

I think that the general rules for NM-B indicate that the big concerns are where the cables are fire-stopped, and where they are surrounded by insulation. This makes sense because there is no opportunity for air flow to carry away heat.

I don't see it often, but it is perfectly legal to use cable ties to secure NM-B, and it would seem to me that it is logical to assume that these would be the situations where the cable would be considered bundled, as opposed to those where other types of fasteners allow the cables to be secured fairly close together - for example, the width of the staple nail or wire. And, it would seem reasonable to assume, the reason there is a blurb about bundling The cable ties can arrange the cables so that some of them are surrounded completely by other cables and therefore can't disapate heat. This is not the situation where one inch or larger holes in adjacent joists has 5 or 6 cables run through them.

The fill in the Arlington cable tray is based on the cross sectional area of the tray. The use of a cable tray has to ignore "bundling" to be a practical method for wiring. It is unlikely that the product would be listed for 40 14-2 cables if it was actually limited to 8 current carrying conductors due to bundling concerns. However, cable trays have a set of rules that apply only when using them. Still, we're talking 80 current carrying conductors here.

[Jerry Peck]

Any comments ... ? The definition is part of the articles scope but none the less bundled is bundled I would think.

From the 2005 NEC:
- (2) Adjustment Factors.
- - (a) More Than Three Current-Carrying Conductors in a Raceway or Cable. Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are stacked or bundled longer than 600 mm (24 in.) without maintaining spacing and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.

From the 2008 NEC:
- (2) Adjustment Factors.
- - (a) More Than Three Current-Carrying Conductors in a Raceway or Cable. Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.

Notice that the bold section shown in 2005 has been re-worded. :)

Also, you did notice what that section applies to, right? That Article has very limited applications. :)

[Roger Frazee]

Yeah I did which is why I said it was defined within the scope of that article none the less we have been using the terminology "bundled" therefore I think when we do use that word it means to be tied together.

Yes the term has been removed and recent testing of cables for overheating ( I'll call it the 'Bundling Effect' :)) shows no use of wire ties. I think the reason is that nm cables can be
in contact with each other in certain installations in such a manner as to constitute the same effect as being tied or wrapped. But we keep saying bundled.....:)

Anyway the cables in that other thread by the op IMO are not bundled or subject to derating for lack of maintaining spacing for 24 inches. Lousy workmanship yes subject to overheating ... my experience tells me no ... how the heck do you span and maintain spacing ... I've always wondered. Also the testing I viewed showed much tighter installation for the 24 inches in a more confined space.

I'd be more concerned with the butchering of those engineered joists than all the nm cables you see.



Now speaking of nm .....


http://i214.photobucket.com/albums/cc172/480sparky/Construction%20methods/romex1.jpg

[Jerry Peck]

But we keep saying bundled.....:)

Not "we" amigo ... "I" keep saying "lack of maintaining spacing" ... :D ... for that very reason.

[Roger Frazee]

Not "we" amigo ... "I" keep saying "lack of maintaining spacing" ... :D ... for that very reason.

OOOPs ....yes you are an 'exception' ....;)

[Raymond Wand]

No bundling at todays inspection. :D

[Joseph Hagarty]

Could not the criss cross of cable be considered bundling?
If not, why not?

http://i214.photobucket.com/albums/cc172/480sparky/Construction%20methods/romex1.jpg

[Roger Frazee]

No bundling at todays inspection. :D

Nope and I have no idea why you would want to install the cables like that ..:confused:

[Jerry Peck]

Could not the criss cross of cable be considered bundling?
If not, why not?

No, but it certainly could be considered "lack of maintaining spacing" if the front cables are not separated from the back cables to allow for air flow.

Looks like a 'conduit runner' was given his first NM cable job and said 'My work is always neat and orderly.' :)

[Joseph Hagarty]

No, but it certainly could be considered "lack of maintaining spacing" if the front cables are not separated from the back cables to allow for air flow.



Yes,
Can not be determined from photos.

[Rollie Meyers]

It's beautiful work, here is a link to where the picture came from for more of the story. It has made the rounds of a lot of forums.

NM Run With An Iron. - ECN Electrical Forums (http://www.electrical-contractor.net/forums/ubbthreads.php/topics/122256/1.html)


Thanks to the OP for posting the pic, it's quite rare to see the care taken like was done in that home...

[Jerry Peck]

It's beautiful work, here is a link to where the picture came from for more of the story. It has made the rounds of a lot of forums.

NM Run With An Iron. - ECN Electrical Forums (http://www.electrical-contractor.net/forums/ubbthreads.php/topics/122256/1.html)


Thanks to the OP for posting the pic, it's quite rare to see the care taken like was done in that home...

Rollie,

Thanks for the link to the other photos and background information - that is one great looking job ... er ... work of art. ;)

[Roger Frazee]

What I noticed was and it made me chuckle is the high end lighting on the joist in my photo.

[Stephen G]

I see spacing blocks between the weave. so there is some gap between the runs...not a sparky but I am paying attention to this thread................more popcorn




Yes,
Can not be determined from photos.

[Jerry Peck]

What I noticed was and it made me chuckle is the high end lighting on the joist in my photo.

You saw that too? Cool.

High end house with high end electrical installation and el cheapo lighting fixture. Sheesh. :)

I would have thought that, on a high end house, they would have finished off the ceiling by installing drywall on it. But hey, what do I know about high end houses? :D