sparky1231
New member
So what is the limit of conductors thru bored holes(300.4(A)(1)?
Number of conductors thru bored holes?
- Thread starter sparky1231
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Depends- are the holes fire stopped? Lots of cable bundled tightly for more than 2 feet??? ........
From the 2014:
334.80:
"Where more than two NM cables containing two or more current carrying conductors are installed, without maintaining spacing between the cables, through the same opening in wood framing that is to be sealed with thermal insulation, caulk, or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(3)(a) and the provisions of 310.15(A)(2), Exception, shall not apply."
310.15(B)(3)(a):
"Where the number of current carrying conductors in a cable or rceway exceeds three or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length exceeding 600mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in table 310.15(B)(3)(a).
Each current carrying conductor of a paralleled set of conductors shall be counted as a current carrying conductor."
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Is this for NM cable? If you asking strictly about the holes themselves the answer is as many as you want as long as there is no fire or draft stop material in the hole. To expand on what User said what happens before and after the holes may trigger one of the other aspects of derating which is lack of spacing for more than 24". That is open to widely different interpretations.
- Location
- Massachusetts
Your veiw on this subject never ceases to confound me.
I cannot for understand why you feel, say five cables run through the same holes in row of studs for longer than 24" is not bundling. It clearly is bundled.
If it is harmful or not is another issue but they are bundled.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Your veiw on this subject never ceases to confound me.
I cannot for understand why you feel, say five cables run through the same holes in row of studs for longer than 24" is not bundling. It clearly is bundled.
If it is harmful or not is another issue but they are bundled.
I tend to agree with infinity. IMO they have spacing in between the joists and are thus not bundled. Now if they were tighter, say tied together with wire ties, then I would say there is little or no spacing so they,are bundled in that case.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
There is no limit. However the more conductors you run the higher any required ampacity adjustments become.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Unless the holes are fire stopped, there would be no derating needed.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
True except for when the cables are considered to be "bundled" for more then 24". Won't say this condition has never been debated here before though. Bottom line usually comes down to how the AHJ sees it though.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Your veiw on this subject never ceases to confound me.
I cannot for understand why you feel, say five cables run through the same holes in row of studs for longer than 24" is not bundling. It clearly is bundled.
If it is harmful or not is another issue but they are bundled.
You're making an assumption on how the cables are installed, there are scenarios where what your suggesting will not apply like running all of the cable through one big hole above a panel. If there is no bundling on either side of the hole then the number of cables within the hole is unlimited.
I'm just answering the question as presented in the OP.
As said previously, you can many cables in the hole. As much as you can fit in. But after certain number you have to derate.
IMO, Once the cables enter the hole the bundling starts, As soon as they exist the hole the bundling stops. So if your hole is not longer than 24" don't worry about bundling. Unless you intentionally bundle them together.
My interpretation of 24" bundling: strapping together using tape, zip tie, tie wire or other means to hold cables together for longer than 24".
IMO, Once the cables enter the hole the bundling starts, As soon as they exist the hole the bundling stops. So if your hole is not longer than 24" don't worry about bundling. Unless you intentionally bundle them together.
My interpretation of 24" bundling: strapping together using tape, zip tie, tie wire or other means to hold cables together for longer than 24".
- Location
- New Jersey
- Occupation
- Journeyman Electrician
The problem is that opinions vary so when one is asked about defining bundling the answers will also vary. I tend to agree with you.
- Location
- Massachusetts
If you read the exception for MC you can clearly tell the CMP feels otherwise
It tells us MC cable supported by bridal rings is bundling.
You guys are nuts
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Laying them all in a corner at the bottom of a stud bay or on top of a top plate could, IMHO, also constitute bundling. But only the AHJ knows for sure. :happyyes:
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Far right in the first picture, maybe. Far left, probably not. :lol:
JFletcher
Senior Member
- Location
- Williamsburg, VA
Heh, never thought to keep scrap nm in my attic. Bundling, kindling, just ugly, I dont know. 334.80 has already been mentioned.
You mean like this?
Is this bundling?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
That is atrocious, but I don't see that meeting the definition of bundling in the dictionary.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Full disclosure: The pics are NOT my install!
I had to do a few jobs at this house and had to be in the attic. The service was moved from the house to an added garage. Looked to be 50-60' from old location to the new.
They just draped the NM over the edge of the addition and along the bottom of the rafters.
One of the jobs was to find a short in an outside light. You will never guess which cable had the short!
Yep, one on the BOTTOM of the bundle/pile of NM!:rant:
I had to do a few jobs at this house and had to be in the attic. The service was moved from the house to an added garage. Looked to be 50-60' from old location to the new.
They just draped the NM over the edge of the addition and along the bottom of the rafters.
One of the jobs was to find a short in an outside light. You will never guess which cable had the short!
Yep, one on the BOTTOM of the bundle/pile of NM!:rant:
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
But since they didn't secure them it made it easier to access that cable now didn't it?
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
But since they didn't secure them it made it easier to access that cable now didn't it?
Bout like hearing the weatherman say:
"Good news folks, instead of getting 12" of snow we only got 11!"
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