boring holes for NM

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Dennis -

I rarely ever get involved in house wiring issues - I'm not in the house wiring business.

However, a similar issue occasionally comes up on derating conductors in short nipples. Between 310.15.A.2 Exception, and 310.15.B.2 the short nipples generally don't matter.

I see now that the discussion appears to center on the NM cables laying on each other between the studs. And my thought, as you said, doesn't apply.

Mike -
I reread section 310.15.A several times. Didn't see any mention of "different ambient temperatures". However, I believe you that it doesn't apply to this discussion.

I now recall some of the reasons I don't get involved in house wiring discussions.

carl
 
Dennis Alwon said:
Marc-
Secondly, you can use 4 2 wire NM cables in a hole since that is only 8 current carrying conductors. If you use #12 then you derate 70% by Table 310.15(B)(2). #12 is rated 30 amps at 90C. 30*.7 is 21 amps -- still good.
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I would expand that to include a total of 4 cables of any combination of either 3-conductor or 2-conductor cables. If it's NM then we're probably looking at 120/240v single-phase. In this case the grounded conductor of a 3-conductor cable wouldn't need to be counted as current carrying.
 
mdshunk said:
I think you're being crazy. Multiple cables through a bored hole are not bundled in my opinion. They're bundled for 1-1/2", then they're not bundled for another 14-1/2". This does not meet the definition of bundling, in my opinion. The inspectors in the jurisdictions where I operate agree with me. I am aware that there are certain hard ass inspectors who have a different opinion, but I'm not sure what they base that on. The inspector is not the AHJ.
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FWIW I agree with Marc based on common sense. Every "wire bundle" I've ever seen or created was zip tied with the intent of holding the wires tightly together, neatly, along the entire length of the bundle. When you pull multiple wires through stud holes, in between these studs the cables are free to fall as they will. This means there is speace between the cables for air cooling.
 
Twoskinsoneman said:
When you pull multiple wires through stud holes, in between these studs the cables are free to fall as they will. This means there is speace between the cables for air cooling.
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I probably ought to drop this topic but I am really having a hard time understanding that concept. Do you think the wires are free to move in different directions and defy gravity. If they are run horizontally the wires will sag-- one will not go up and the other go down. If the wires are touching it is bundling. There is no way you can run them horizontally through the same holes and not have then touch the entire length.

This is all sort of moot because electricians rarely drill a hole large enough for more than 3 conductors when installing wires horizontally.
 
Dennis Alwon said:
I probably ought to drop this topic but I am really having a hard time understanding that concept. Do you think the wires are free to move in different directions and defy gravity. If they are run horizontally the wires will sag-- one will not go up and the other go down. If the wires are touching it is bundling. There is no way you can run them horizontally through the same holes and not have then touch the entire length.

This is all sort of moot because electricians rarely drill a hole large enough for more than 3 conductors when installing wires horizontally.
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Well again it's only my opinion based on personal experience and observation, but yes due to the stiffness of a solid conductor, it will "defy gravity" by trying to retain its form. It had been coiling up for a long time (relative), and after being pulled through the holes in the studs it just doesn't lie flat perfectly straight. It tends to want to lift and separate from the other cables.
I think if you add addition ties in between the places its supported through the studs we could call in bundled.
 
I'm gonna throw a photo into the thread here.

Is this what we're discussing?:

Bundle.JPG


They are not touching each other the entire length. And they definately do not sag. Some are going up. Some are going down. There's space between them. IMPO, these are not bundled. For those who are wondering, no I did nothing to these cable after I pulled them in. This is how the naturally ended up. I did not spread them apart to create any space between them, and I did not take the photo just for this thread. I took it almost a year ago.
 
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480sparky said:
IMPO, these are not bundled.
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It would be the inspector opinion that will matter.:)

This is how it is defined in 2002 NEC 520.2.

Bundled. Cables or conductors that are physically tied, wrapped, taped, or otherwise periodically bound together.
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The NM in that over sized photo look periodically bound together to me.

As side note to all members please make sure images are no larger than 600 pixels in any direction.
 
480sparky said:
This was in a dwelling.
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LOL, I did not think it was a theater or a TV studio.

IMO it would be reasonable to apply this definition of bundling found in 520 to all uses of the word bundled in the NEC.

Member bphgravity put in some sort of proposal to add that definition to Article 100. I believe it was rejected, I do not recall why.
 
What is the problem with drilling a Hole for every wire? I'm sorry But when I see multiple wires in a single hole it just doesn't look right. How do you pull them in without damaging the sheathing? I guess when in Rome do what the Romans do.
 
iwire said:
IMO it would be reasonable to apply this definition of bundling found in 520 to all uses of the word bundled in the NEC.
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It might be reasonable, but it's not an enforcable definition in this case.
 
iwire said:
Member bphgravity put in some sort of proposal to add that definition to Article 100. I believe it was rejected, I do not recall why.
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It was accepted. 10-2.
bundle2.JPG


splinetto said:
How do you pull them in without damaging the sheathing?
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Easy. Hint: I remember the Kennedy administration.
 
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splinetto said:
What is the problem with drilling a Hole for every wire? I'm sorry But when I see multiple wires in a single hole it just doesn't look right. How do you pull them in without damaging the sheathing? I guess when in Rome do what the Romans do.
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???

Run much romex?
 
splinetto said:
You have to clue me into what you mean
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I think he's telling you that he's pulled old braided romex, and thermoplastic romex is way easier. Now they're shipping that slick romex... it practically installs itself in the holes.
 
I would think Table B.310.11 would apply to residential or any non continuously loaded circuits.The chances of all the cables drawing any significant amperage at the same time are slim.I think this would be load diversity.
Rick
 
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