# 9 wire into conduit



## 360max (Jun 10, 2011)

Tom67 said:


> Any one remember, what article says about 9 wire into one conduit??


...you can put more than 9 wires in a conduit, I think your referring to the derating 310.15 with specific reference to table 310.15.b.2.a (08 NEC).

You can use the 90 degree column of 310.16 for derating. So a # 12 wire (90 degree column) is good for 30 amps. Now if you have 9 conductors in the pipe, 310.15.b.2.a states you must derate or adjust to * 70%*, which comes out to 21 amps, which is good for a 20a circuit breaker (*.7*x30). 

So you can run up to 9 (nine) #12 current carrying conductors in the same pipe and connect them to 20 amp circuit breakers maximum . Hope this helps.


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## HARRY304E (Sep 15, 2010)

360max said:


> ...you can put more than 9 wires in a conduit, I think your referring to the derating 310.15 with specific reference to table 310.15.b.2.a (08 NEC).
> 
> You can use the 90 degree column of 310.16 for derating. So a # 12 wire (90 degree column) is good for 30 amps. Now if you have 9 conductors in the pipe, 310.15.b.2.a states you must derate or adjust to * 70%*, which comes out to 21 amps, which is good for a 20a circuit breaker (*.7*x30).
> 
> So you can run up to 9 (nine) #12 current carrying conductors in the same pipe and connect them to 20 amp circuit breakers maximum . Hope this helps.


Good work inside of 3 minutes.....:thumbup:


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## wireman64 (Feb 2, 2012)

Tom67 said:


> Any one remember, what article says about 9 wire into one conduit??


O man


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## acro (May 3, 2011)

360max said:


> You can use the 90 degree column of 310.16 for derating. So a # 12 wire (90 degree column) is good for 30 amps. Now if you have 9 conductors in the pipe, 310.15.b.2.a states you must derate or adjust to * 70%*, which comes out to 21 amps, which is good for a 20a circuit breaker (*.7*x30).


What is the reasoning on using the 90 degree column for derating. I thought you would have to use the proper terminations also to be able to use that column.

Are you saying that with "normal" 75 degree terminations, you can use the higher ampacity of the 90 degree column for all derating calculations? Assuming the wire is 90c rated.


Found this but maybe you can summarize it for us.
http://www.mikeholt.com/mojonewsarc...C-Conductor-Ampacity-for-Feeders~20040914.php


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## Greg (Aug 1, 2007)

You can use the 90C column for derating purposes but the OCP can not exceed the 60C column or in this instance 240.4(D)('05 NEC), 12AWG wire OCP 20A, because I assume they are general purpose branch circuits and not motor circuits. Technically speaking you also have to apply any temperature corrections after your pipe fill calculation.

All I have at the house is an '05 NEC for the article reference.


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## CTshockhazard (Aug 28, 2009)

acro said:


> What is the reasoning on using the 90 degree column for derating. I thought you would have to use the proper terminations also to be able to use that column.
> 
> Are you saying that with "normal" 75 degree terminations, you can use the higher ampacity of the 90 degree column for all derating calculations? Assuming the wire is 90c rated.


When calculating the ampacity of the conductor through deration, you are doing just that and only that, the _ampacity of the conductor_.

Once you have established the ampacity of the conductor, it must be equal to or exceed the ampacity of the terminal and/or device.



> 110.14(C) Temperature Limitations. The temperature rating associated
> with the ampacity of a conductor shall be selected
> and coordinated so as not to exceed the lowest temperature
> rating of any connected termination, conductor, or device.
> ...


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## 480sparky (Sep 20, 2007)

CTshockhazard said:


> When calculating the ampacity of the conductor through deration, you are doing just that and only that, the _ampacity of the conductor_............



'Xactly.



> *310.15(B)(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 in Table 310.15(B)(3)(a)._................


There is nothing there which references 110.14(C). Once you do this, THEN you get into terminations, rooftops, ambient temperature, voltage drop, etc.


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## 360max (Jun 10, 2011)

acro said:


> What is the reasoning on using the 90 degree column for derating. I thought you would have to use the proper terminations also to be able to use that column.
> 
> Are you saying that with "normal" 75 degree terminations, you can use the higher ampacity of the 90 degree column for all derating calculations? Assuming the wire is 90c rated.
> 
> ...



*for an excellent explanation *
http://www.mikeholt.com/instructor2/img/product/pdf/1259687476sample.pdf see NEC section 310 on pages 121, 122, 123 (purple page #'s)


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## 360max (Jun 10, 2011)

480sparky said:


> 'Xactly.
> 
> 
> 
> There is nothing there which references 110.14(C). Once you do this, THEN you get into terminations, rooftops, ambient temperature, voltage drop, etc.


...you also have to take into consideration the temp rating of the conductor


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## icefalkon (Dec 16, 2007)

When we cover this in the Apprenticeship we use T.A.T.

Temperature

Ampacity

Termination

To remember the order.


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## frenchelectrican (Mar 15, 2007)

icefalkon said:


> When we cover this in the Apprenticeship we use T.A.T.
> 
> Temperature
> 
> ...


Here mine verison which we use A.T.T.

Ampacity
Température
Terminaison

That how I run all the time


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## ralpha494 (Oct 29, 2008)

I like that! ATT is easier to remember. 

Blau ist schoen.


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## TGGT (Oct 28, 2012)

Here's a question. "9 current carrying conductors". 

Are you including the neutral as a current carrying conductor? 310.15(B)(5)(a) states: A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15(B)(3)(a).

That would mean you'd only be counting 4 ungrounded conductors (80%). Am I interpreting "the unbalanced load"incorrectly?

EDIT: "9 wires" is what I would interpret as 4 hots, 4 neutrals, and 1 ground. The ground is not to counted when derating, though it does count for fill. That's what I'm seeing here.


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