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Joined: Jul 2004
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I have been digging through dusty ROPs all evening and I came up with 3 that seem appropriate to what NFPA is thinking. This is the initial 2005 proposal substantiation. Substantiation:
Code-Making Panel 6 Rejected Proposal 6-31 to add the proposed text to 310.15(B)(2)(a)
and provided the following Panel statement:"The Panel agrees with the intent of the Proposal,
however, this material is more appropriately addressed in 334.80 since the Proposal only
applies to one type of cable, and Code-Making Panel 6 covers all wiring methods. Therefore,
Code-Making Panel 6 has forwarded this Proposal to Code-Making Panel 7 for action."
The substantiation provided by the submitter, Travis Lindsey, of Proposal 6-31 was:"Recent
experimentation shows the possibility of dangerous conditions when loaded circuits are
brought into close proximity to each other inside a fire- or draft-stop, where the ability to
dissipate heat is extremely limited. Cable temperatures well in excess of their 90°C
rating were encountered, with no overcurrent protection present for these conditions.
Results indicate that immediate adjustments should be made to the NEC to apply at
least to the specific case represented by the experiment. Such a proposal is being
made, with a supplemental report offered as technical support. Our old buddy Mike Holt suggested that they should just drop the whole paragraph for the 2008 pointing out these are only bundled for 3-4" in the foam (with a lot of other verbiage) He got this response Technical substantiation submitted during the 2005 Code
cycle supported the addition of the second paragraph in 334.80. While the
cable is only bundled for a short distance within the fire- or draft-stopped wood
framing, it is long enough that the insulated conductors exceed their allowable
temperature rating. Frederick Hartwell proposed it again for the 2011 and got this The panel rejects the deletion of the second paragraph since local practice is
not justification for national code rules, and the submitter did not provide
sufficient proof to counter the research presented in previous code cycles. Nobody addressed it for the 2014 I am still trying to track down that report they used to justify the original 2005 change but the NFPA web site is miserable. Putting something in their search bar does not seem to affect the 30 pages of hits that it responds with.
Greg Fretwell
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Unfortunately 334.80 does not specify a distance. If they are bundled in a bored hole in wood and foamed in, that is a violation. How so? 334.80 will end up @ Table 310.15(B)(3)(a) , where under 24" is not a problem ~S~
Last edited by sparky; 02/19/16 09:23 AM.
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Joined: Jul 2004
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Table 310.15(B)(3)(a) does not mention "24" or any other length. 334.80 refers to the table not the article.
If you read the comments in the ROP it is clear NFPA is concerned about that 3" section that is buried in foam and they say it does act differently than wires in a pipe.
I would still like to see the study that prompted the change in 2005 but I have not found it yet.
Greg Fretwell
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This is a first for me then Greg
Since when has the NEC required a table w/o requiring the applicable codes to it ?
~S~
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Joined: Jul 2004
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I suppose the real answer is in the style manual somewhere but it seems clear NFPA is talking about >9 90c CC conductors in NM jackets in 3" of foam in a bored hole, in wood, just based on what CMP7 says in the ROPs
Greg Fretwell
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With all due respect Greg, In this situation a code ref for derating doesn't rate the privilege of a 90.4, it's far to cut/dry
Nor can i (et all EC's) be a competitive biz based on some study being batted around the CMP's.
Further, why would it be necessary for any CMP to reinvent the wheel foisting some 'study' when other countries /electrical codes (most are IEC spin offs) have already had a handle on the issue for decades?
IMHO, we have a system of deaf copperholic based rationale going on here....
~S~
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I am just an old inspector, not an umpire.
I am not sure how I would deal with this in the field but I doubt it would come up. That is a lot of wire to get in a hole.
If you are taking out that big a hole, why not just take out a big slice (the structure was already away), lace out the cables on a wide running board and let them foam that in.
Greg Fretwell
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I'm an old EC that looks to my AHJ's for solid answers Greg. In past cases like this it's considered the job (tax subsidized at that) of the NEC ,CMP.s ect to provide the tools needed for field decisions. We have ,in the past, asked for formal interpretations from Batterymarch park. Were you and i toe/toe on the job, i'm sure i'd suggest it. In fact, just this exchange alone should inspire us toward such a goal, if you're game...:) That said , the best ahj's look for ways to pass a job vs. failing it, so i appreciate your 'big slice' suggestion, and would like to up the ante' with a sleeve....to forgo any mass burial of nm in foam...>>> I refer you to Chap 9 tables....where i can stuff as many nm's as i can fit in a piece of sch 40.... Notes to Tables
(I) See Informative Annex C for the maximum number of
conductors and fixture wires, all of the same size (total
cross-sectional area including insulation) permitted in
trade sizes of the applicable conduit or tubing.
(2) Table I applies only to complete conduit or tubing systems
and is not intended to apply to sections of conduit or tubing
used to protect exposed wiring from physical damage. ~S~
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Joined: Jul 2004
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I am just reading what CMP 7 has said about the second paragraph of 334.80.
Your AHJ can read it any way they want and you are right, that is what matters. Just be aware, the next inspector who shows up may have actually read the ROP.
My wife is running into this where she works with the life safety officer. Things that were fine for 20 years suddenly became a violation when they went from county code enforcement to city code enforcement (different AHJ) with no changes to the language of the code.
Greg Fretwell
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I'm running into the same situation where I'm trying to upgrade a century-old installation but it appears that the AHJ would rather that I just leave it as a firetrap since I won't tear out structure that has served perfectly since the late 1800's...but doesn't meet the strict letter of this years' Code.
Ghost307
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