4 14 nmb through 1 drilled hole

[winnie]

so what do we do with 12-2-2 ?

~RJ~

Derate to 80% of the base 90C ampacity...giving you 24A which exceeds the allowable 20A breaker size, so non-issue for most general purpose circuits.

Jon

 

[LarryFine]

so what do we do with 12-2-2 ?

Still one cable.

 

[wwhitney]

So suppose you drill a 7/8" hole through a 2x, and bang in a 1-1/2" length of the plastic channel pictured below. [The diagonal is 0.9", so I think it should friction fit.] And then you pass one NM cable through each of the 4 openings created, and then foam the whole thing. Have you successfully sidestepped the 334.80 requirement? Either by (a) creating 4 holes instead of 1, or (b) "maintaining spacing"?

Not important with #14 or #12 NM with just 8 CCCs, but would matter with more than 9 CCCs. Which might require a larger overall hole and divider.

Cheers, Wayne

 

[romex jockey]

Still one cable.

yeah Larry......b.b.b.but....>>>

310.15(B)(3)(a) Adjustment Factors.

(a) More Than Three Current-Carrying Conductors. Where the number of current-carrying conductors in a raceway or cable exceeds three,

~RJ~

 

[infinity]

yeah Larry......b.b.b.but....>>>

310.15(B)(3)(a) Adjustment Factors.

(a) More Than Three Current-Carrying Conductors. Where the number of current-carrying conductors in a raceway or cable exceeds three,

~RJ~

Did you see post #20, that cable is 4 CCC's.

 

[Strathead]

See 334.80.

thanks, that is what I get for never touching NM cable

 

[romex jockey]

Did you see post #20, that cable is 4 CCC's.

yes, so do we run 10-2-2 for 20A circuits now, or does the 24" rule apply for 2" of fire caulked holes for 12-2-2 ?

~RJ~

 

[winnie]

We run 12-2-2 for 20A circuits.

The derating rule applies. But you derate from the actual ampacity of the conductors...and get a value that exceeds what we are allowed to use because of the 'small conductor rule's. So in this case the requirements for derating don't make a practical difference n

Jon

 

[infinity]

yes, so do we run 10-2-2 for 20A circuits now, or does the 24" rule apply for 2" of fire caulked holes for 12-2-2 ?

~RJ~

The 24" bundling rule and the fire stopped hole rule are two different requirements not dependent on each other.

 

[don_resqcapt19]

yes, so do we run 10-2-2 for 20A circuits now, or does the 24" rule apply for 2" of fire caulked holes for 12-2-2 ?

~RJ~

Two 12-2-2 cables are still fine on a 20 amp OCPD even with the required ampacity adjustment. NM conductors are 90°C conductors and the ampacity adjustment starts with the 90°C ampacities. An ampacity adjustment for 10 AWG, 90°C and smaller conductors does not really change anything for the installation until you exceed 9 conductors.

 

[romex jockey]

The 24" bundling rule and the fire stopped hole rule are two different requirements not dependent on each other.

so your going to tell me i can stuff a 23" nipple with as many 12-2-2's as i can fit (notes to cp 9 not applicable), but not run a 12-2-2 thru 2" of foam????

~RJ~

 

[romex jockey]

Two 12-2-2 cables are still fine on a 20 amp OCPD even with the required ampacity adjustment. NM conductors are 90°C conductors and the ampacity adjustment starts with the 90°C ampacities. An ampacity adjustment for 10 AWG, 90°C and smaller conductors does not really change anything for the installation until you exceed 9 conductors.

334.80 referrers to table 310.15(B)(3)(a) Don

in one passage it accepts the exception to Table 310.15(B)(3)(a)., in the other it claims 310.15(A)(2), does not apply

310.15(B)(3)(a) Adjustment Factors.

(a) More Than Three Current-Carrying Conductors. 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 31o.15(B)(3)(a).

some clarity would be appreciated

thx

~RJ~

 

[infinity]

so your going to tell me i can stuff a 23" nipple with as many 12-2-2's as i can fit (notes to cp 9 not applicable), but not run a 12-2-2 thru 2" of foam????

~RJ~

That is exactly what it says in 334.80.

 

[romex jockey]

That is exactly what it says in 334.80.

i believe there is a code loop infinity

~RJ~

 

[Fred B]

334.80 talks about "derating" if 2 or more installed thru hole without maintaining space. Question, how much space does it need to not need to be adjust? It doesn't seem to define space.

 

[infinity]

334.80 talks about "derating" if 2 or more installed thru hole without maintaining space. Question, how much space does it need to not need to be adjust? It doesn't seem to define space.

Actually it says more than 2 cables, but you're right can you actually maintain spacing in a single hole and if so how large does it need to be?

 

[wwhitney]

I tried to raise that question in post #23, but got no response.

Cheers, Wayne

 

[romex jockey]

I tried to raise that question in post #23, but got no response.

Cheers, Wayne

well your aim is the 'rule of 9' Wayne, so is Don's , 334.80 will take you there, but two separate 'hard to read' passages make some translation appreciable

seriously , i can't believe i pay tax $$$'s for people to write regulatory bureaucracy to the point where we need to even ask this

~RJ~

 

[Fred B]

But how much space is needed to be able to dissipate heat on conductors?

 

[romex jockey]

But how much space is needed to be able to dissipate heat on conductors?

and how is the math applicable Fred?

consider 376.22 , why does the NEC do '30', and the CEC '200'?

~RJ~