Bundling Question

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A/A Fuel GTX

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Running multiple parallel home runs through the same holes in floor joists across the length of the home in typical residential construction......Bundling?

Running two or three parallel SER feeders through the same holes in floor joists across a multi family dwelling....Bundling?

312.5 (C) Exception..... more than 24"........Bundling?

I would say yes and derating is required. Other opinions?
 
This study offers a good argument for adjusting at much shorter lengths when cables are "bundled" less than 24"

http://www.copper.org/applications/electrical/building/pdf/bundle_evaluation_report.pdf

From the summary


Statistical evaluation of the data indicated that outdoor temperatures as low as 87 F, in
combination with 73% loading of all the cables, could trigger bundle temperatures in excess of
the cables? 194 F rating. This extends a level of concern to all areas of the USA, not just to hot
locations such as Las Vegas.
It is recommended that the NEC institute de-rating for bundled NM-type cables in wood topplates
at much smaller lengths than 24 inches.​
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tallguy said:
When was the last time you heard the evening news open with "The 5-alarm blaze was determined to be caused by overheated cabling bundled in joists"??
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I find it amazing to watch a large fire on TV, then officials will hold a press conference or an official will speak with the press. All the reporters ask "What started the fire?" The standard response is "We don't know yet." Evidence is gathered, analyzed, tested and recorded. Notes are taken. And video and photos as well. Witnesses are interviewed. Police officers take statements. If they're fortunate enough to be able to afford it, a dog will be brought in to give the site a sniff or two.

So it can take months, if not years, for the fire marshal's office and other investigators to determine the actual cause of a fire. And after that long, it's old news that never makes it into the media and press. Think of airplane crashes. How long did it take to determine the true cause of the plane crash at Lockerbie, Scotland?
 
480sparky said:
So it can take months, if not years, for the fire marshal's office and other investigators to determine the actual cause of a fire.
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I was oversimplifying in order to make the point... Nevermind a fire, can anyone cite an example of cable running through joists deteriorating prematurely due to overheating?

Regarding causes of fires, I saw an interesting video about 10-15 years ago about a convenience store fire which was pinned on "faulty electrical wiring". They could point right to the box that was the "culprit". Upon reviewing the security camera videotape, however, they could clearly see that the clerk had failed to stub out his/her cigarette properly, dropped it in the can, and locked up the store for the evening. 10 minutes later...

It's an inexact science, to be sure. So, I'll throw down the gauntlet for anyone to provide an example of cable bundled through joists deteriorating prematurely due to overheating.
 
m73214 said:
I would say yes and derating is required. Other opinions?
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My opinion for what it is worth that it is bundling in spite of the fact that you will probably never see any ill effects from it.

We have had this arguement before but you asked opinions so you got mine.
 
M. D. said:
This bulletin is from NEMA they refrence a study done in tronto 22 years ago ,.. the revised date on this is 8/07. I'll try to find the study .

http://www.nema.org/stds/eng-bulletins/upload/Bulletin%2095%20Rev%202007%20NM%20Cable%20encased%20in%20spray-foam%20insulation.pdf
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MD--- wha does this have to do with NM cable running through the joists. This study is about encased in spray foam not bundling. Although interesting I don't believe it is what the OP was questioning.
 
Dennis is right......I'm just looking for opinions/code references on just exactly what bundling is. It is not in Article 100. Wouldn't the conductors in MC cable be considered "bundled"? I don't know which way to go here....
 
m73214 said:
Dennis is right......I'm just looking for opinions/code references on just exactly what bundling is. It is not in Article 100. Wouldn't the conductors in MC cable be considered "bundled"? I don't know which way to go here....
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You have me confused NM or MC cable. Look at art. 310.15(B)(2)
 
I'm just kind of rambling here but the very nature of the way MC cable is constructed sort of bundles the conductors in the twisted fashion they are assembled. Just over-analyising again.....
 
Well,.. it has to do with adjusting ampcity I posted the bulletin because someone suggested that they study I linked might be corrupt because of the interest of the copper industry to sell copper. I thought if I could find the study done at the University of Toronto it might offer another view , as the bulletin suggests .

As for the O.P. ,NM cables that are bundled are required to be adjusted , take a look at them and ask yourself if they are a bundle of 24"
 
I wouldn't worry about MC...take a look at 310.15(B)(2)Exception 5

the part about a 60% adjustment factor
 
emahler said:
I wouldn't worry about MC...take a look at 310.15(B)(2)Exception 5

the part about a 60% adjustment factor
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Yeah up to 20 current carrying conductors.
 
m73214 said:
Running multiple parallel home runs through the same holes in floor joists across the length of the home in typical residential construction......Bundling?
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How can it be bundled when the joist is typically only 1 1/2"???, worst case scenario you drill through a triple... :-? Most of the houses I wire now use I-joist anyways... they are only 1/2" thick...
 
M. D. said:
Well,.. it has to do with adjusting ampcity I posted the bulletin because someone suggested that they study I linked might be corrupt because of the interest of the copper industry to sell copper.
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Not saying that the study is necessarily corrupt. I would venture to say though that the copper industry wouldn't be promoting a study which found that derating wasn't necessary.
 
stickboy1375 said:
How can it be bundled when the joist is typically only 1 1/2"???, worst case scenario you drill through a triple... :-? Most of the houses I wire now use I-joist anyways... they are only 1/2" thick...
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My theory on this is that the wires are only going through a 1/1/2" hole but they are often still bundled together in the space beteen the joist.

Drill a 1" to a 1 1/2" hole through a bunch of joists and fill it with wires. I bet they are bundled in the space between joists.

As a rule I just don't put more than 4 12/2 or 14/2 or combo of the them in holes that go through 2 or more joists spaces.

If there are going to lots of cables running in an area I will often make the builder build a chase. In basements we often have duct chases and plumbing chases to use so we don't have tons of holes to drill.
 
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