[vinroc]

I have a situation where I have up to five NM 12 and 14 AWG cables bundled.

How do I show the inspector i have considered derating?

 

[don_resqcapt19]

I have a situation where I have up to five NM 12 and 14 AWG cables bundled.

How do I show the inspector i have considered derating?

What loads are served by these cables?

If they are receptacle loads, the #14s are no longer suitable for use as a 15 amp circuit, and the maximum OCPD (over current protective device) for the #12s would be 15 amp.

If they are not receptacle loads, the maximum OCPD for both sizes of wire would be 15 amps, and you would have to show a load calculation of 12.5 amps or less for the #14s and 15 amps or less for the #12s.

 

[Bugz11B]

I always have bundles (load calc's in my notebook) I have never had a inspector say a word to me except 1 time when I had about 15 NM runs bundled for about 30' they were all "Vantage" switch legs, he asked I opened my notebook he didnt even look just took my word for it.

 

[Semi-Ret Electrician]

IMO this is a nightmare to enforce and really has never cause a problem in resi work, where the entire home pulls and average current of 30A, per some POCO's

Just what constitutes "maintaining spacing"?

Some folks ty-wrap/bundle conductors in panels for over 24" should they derate?

(3) 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 inTable 310.15(B)(3)(a).

 

[chicken steve]

Just what constitutes "maintaining spacing"?

where there is 'space' i suppose.....

here, land of manufactured zipper homes, we'll often receive them with two distinct bundles, each about 2" in diameter, one made made into the panel, the other with enough slack to reach the panel

Often the undersides of these units will simply extend a 2" hole , incorporating all wiring, to fan out as it becomes distal of the panel

two floor 'stackable zipper homes' incorporate a 2" sch 40 sleeve on either side, all the NM stuffed on in & down to the panel location

~CS~

 

[Semi-Ret Electrician]

where there is 'space' i suppose.....

here, land of manufactured zipper homes, we'll often receive them with two distinct bundles, each about 2" in diameter, one made made into the panel, the other with enough slack to reach the panel

Often the undersides of these units will simply extend a 2" hole , incorporating all wiring, to fan out as it becomes distal of the panel

two floor 'stackable zipper homes' incorporate a 2" sch 40 sleeve on either side, all the NM stuffed on in & down to the panel location

~CS~

What you say was very common here as well.

The cable tray folks say one cable diameter is OK. IMO, the NEC needs to tweek that section a little better.

I wonder how many "bundling" corrections are cited? Pete?

 

[don_resqcapt19]

IMO this is a nightmare to enforce and really has never cause a problem in resi work, where the entire home pulls and average current of 30A, per some POCO's

Just what constitutes "maintaining spacing"?

Some folks ty-wrap/bundle conductors in panels for over 24" should they derate?

(3) 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 inTable 310.15(B)(3)(a).

In most cases the Exception to 310.15(A)(2) will permit bundling in the panel without derating.
Also, CMP 6 is on record in their action on proposal 6-44 for the 2014 code as saying that the derating rules only apply to conductors in cables and raceways.

Panel Statement: Section 310.15(B)(3)(a) is specific to conductors in raceway or cable. This section provides references to other sections, but contains rules for only conductors in raceways or cables.

 

[Shockdoc]

I still often drill a 2 5/8 " hole and pull 18 cables thru it, been doing it like that for 25 years, don't see no reason to change my ways now.