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.
