bundling

[John Arnold]

Candidates for de-rating, or re-routing to provide sufficient spacing for heat dissipation, yes?

[Jon Randolph]

I would not call for de-rating as I think that there would be suficient air movement to faclitate coolling.

However, I would call for the duct contact and the improper holes in the joists as well as the fire hazard with the vapor barrier uncovered.

[John Arnold]

I would not call for de-rating as I think that there would be suficient air movement to faclitate coolling.
I don't know. They're pretty crammed together, and for much longer than 24 inches.

[Jerry Peck]

Candidates for de-rating, or re-routing to provide sufficient spacing for heat dissipation, yes?

Definitely.

Spacing has not been maintained. Derating is needed if left there like that.

Now, what about the location (within the floor joists - some look real close to the bottom of the joists) and size of those holes?

[Jon Randolph]

I thought that de-rating applied to 3 or more current carrying conductors within a chase in excess of 24" length. I view a chase as small confined area such as conduit. I do agree that they are bunched up together pretty tight at each joist, but the joist width is much less that 24". I would think that any additional heat would dissipate between the joists.

[John Arnold]

I thought that de-rating applied to 3 or more current carrying conductors within a chase in excess of 24" length....

IRC says "stacked or bundled for distances greater than 24 inches without maintaining spacing and are not installed in raceways..."

[Bruce King]

This link is a good example of bundling.

Romex bundling - InterNACHI Message Board (http://www.nachi.org/forum/showthread.php?t=27415)

The tyraps must have cut through a cable.

Note how the main burned area is not the same under the 2nd tyrap. Similar operational "heat" under both tyraps and only one cooked.

[Jerry Peck]

IRC says "stacked or bundled for distances greater than 24 inches without maintaining spacing and are not installed in raceways..."


This is the key phrase "without maintaining spacing".

That addresses electricians who state "it is not bundled" ... does not have to be "bundled" in the sense that it must be wrapped tightly together with bands or straps ... it only must be "without maintaining spacing" - meaning straps/bands/whatever or no ... don't "maintain spacing" and you have to derate it.

[Richard Abrams]

These would not have to be derated unless the cavity was filled with insulation compond. SEE NEC 2008 334.80

[Jerry Peck]

These would not have to be derated unless the cavity was filled with insulation compond. SEE NEC 2008 334.80


Close but no cigar.

From the 2008 NEC. (underlining is mine)
- 334.80 Ampacity.
- - The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The ampacity shall be in accordance with the 60°C (140°F) conductor temperature rating. The 90°C (194°F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60°C (140°F) rated conductor. The ampacity of Types NM, NMC, and NMS cable installed in cable tray shall be determined in accordance with 392.11.
- - 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 fire- or draft-stopped using thermal insulation, caulk, or sealing foam, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a) and the provisions of 310.15(A)(2), Exception, shall not apply.
- - Where more than two NM cables containing two or more current-carrying conductors are installed in contact with thermal insulation without maintaining spacing between cables, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(2)(a).

We are not JUST referring to where they go through the wood framing, but to the entire run visible in the photo, which needs to be in accordance with:

From the 2008 NEC. (underlining is mine)
- 310.15 Ampacities for Conductors Rated 0–2000 Volts.
- - (B) Tables.
- - - (2) Adjustment Factors.
- - - - (a) More Than Three Current-Carrying Conductors in a Raceway or Cable. Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.

[John Allingham]

Not sure how it is down there, but up here cables must be 1" minimum from the heating ducts as well.

[Tom Dietrich]

Might be more concerned about how close the wires are to the bottom edges.

tom