# derating your conductor if >3 of them.



## HARRY304E (Sep 15, 2010)

kaboler said:


> It seems that nearly every job I go to, people forget to derate the wire if there's more than 3 conductors in a raceway.
> 
> Good thing that people prefer BX than conduit, because.. tired of talking.


:wacko::wacko::w00t::laughing:


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## TOOL_5150 (Aug 27, 2007)

This thread is dildos.


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## Shockdoc (Mar 4, 2010)

So I guess I'll have to upsize to 10/4 mc now on all my 20 amp mwbc feeders.:no::laughing:


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## Bkessler (Feb 14, 2007)

kaboler said:


> It seems that nearly every job I go to, people forget to derate the wire if there's more than 3 conductors in a raceway.
> 
> Good thing that people prefer BX than conduit, because.. tired of talking.


People Also forget derating is based on 90c and generally not a factor until #9.


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## chicken steve (Mar 22, 2011)




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## Bulldog1 (Oct 21, 2011)

Please explain in detail how you know that derating was not done? :whistling2:


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## Bulldog1 (Oct 21, 2011)

Bkessler said:


> People Also forget derating is based on 90c and generally not a factor until #9.



People may forget but real electricians? :no:


You are correct until 9 CCC you don't have to worry. The reason is almost all wire is 90 deg rated now. In the old days it was not.


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## Dennis Alwon (May 9, 2009)

It is a disservice to state that de-rating is only effective when you have 9 CCC. That may be true for #12 or #14 but not necessarily for larger size wires. You must derate when you have 4 CCC and that can make a difference with larger size wires esp. when in parallel.


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## BBQ (Nov 16, 2010)

Dennis Alwon said:


> It is a disservice to state that de-rating is only effective when you have 9 CCC. That may be true for #12 or #14 but not necessarily for larger size wires. You must derate when you have 4 CCC and that can make a difference with larger size wires esp. when in parallel.


I agree.

Basically '9' only works with 14, 12 & 10 AWG used for typical circuits and I think that has more to do with 210.4(D) than anything else.


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## Bulldog1 (Oct 21, 2011)

Dennis Alwon said:


> It is a disservice to state that de-rating is only effective when you have 9 CCC. That may be true for #12 or #14 but not necessarily for larger size wires. You must derate when you have 4 CCC and that can make a difference with larger size wires esp. when in parallel.





When I read the op's post my mind envisioned a 3/4 conduit full of small conductors. 
I was talking only about small conductors. I forget you can't read my mind. My point was anything over 3 ccc in the old days had to be derated because all wire was not 90 degree.


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## chris856 (Jun 12, 2009)

As far as #12 is concerned I just say "nine and your fine".


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## chris856 (Jun 12, 2009)

Bulldog1 said:


> I was talking only about small conductors. I forget you can't read my mind. My point was anything over 3 ccc in the old days had to be derated because all wire was not 90 degree.


 Our beloved OP has not worked anywhere near a time when the majority of our wires were not 90 degrees. Romex, THHN, or whatever, as far as bundleing is concerned, most of our wire is 90 degree rated these days.


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## chris856 (Jun 12, 2009)

At least you WANT to be knowledgable at this stuff, unlike a lot of my peers, you just need to do a little research before you make such bold statements.


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## Bulldog1 (Oct 21, 2011)

chris856 said:


> Our beloved OP has not worked anywhere near a time when the majority of our wires were not 90 degrees. Romex, THHN, or whatever, as far as bundleing is concerned, most of our wire is 90 degree rated these days.[/QUOTE
> 
> 
> 
> I was pointing out now days you don't always have to derate if you have over 3 wires BECAUSE almost all wire is rated 90 degrees now.


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## Bulldog1 (Oct 21, 2011)

chris856 said:


> At least you WANT to be knowledgable at this stuff, unlike a lot of my peers, you just need to do a little research before you make such bold statements.





We were talking about small conductors. I posted a comment about small conductors. I don't need to do "research" I know this crap. But I will give you I need to stop being lazy and post complete thoughts so everyone knows what I am trying to say.


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## BBQ (Nov 16, 2010)

Bulldog1 said:


> My point was anything over 3 ccc in the old days had to be derated because all wire was not 90 degree.


Is it 90C or is it 210.4 that requires us to use oversized conductors from the start for 15, 20 & 30 amp circuits?

Or is it both?


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## wildleg (Apr 12, 2009)

Bulldog1 said:


> chris856 said:
> 
> 
> > Our beloved OP has not worked anywhere near a time when the majority of our wires were not 90 degrees. Romex, THHN, or whatever, as far as bundleing is concerned, most of our wire is 90 degree rated these days.[/QUOTE
> ...


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## 480sparky (Sep 20, 2007)

This 'nine is fine' logic is a classic example of creating 'shortcut' that ends up being misunderstood and wholely misused.

I think a lot of fledgling electricians manage to stumble across the small-conductor 'Nine Rule' on their own. So over the years, they use this rule-of-thumb instinctively. As the years wax & wane, they end up working with less-knowledgeable noobs, who are off-handedly informed of this wondrous and mysterious 'Nine is Fine' concept.

Suddenly, the noob thinks, "Gee, as long as I don't exceed nine wires in a pipe, I don't have to bother with any derating calculations! Kewl!!!"

And thus is born yet another Urban Legend Electric Code section. Just like _No Wire Nuts in a Panel_, _Raceways Cannot Exceed 100'_, _#12 Wire must Be on a 20a Breaker_, _NM Is Made With THHN_, etc.


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## Bulldog1 (Oct 21, 2011)

We are talking about derating. Did you even read the thread?


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## 480sparky (Sep 20, 2007)

Bulldog1 said:


> We are talking about derating.


Uh, so am I.



Bulldog1 said:


> Did you even read the thread?


Did you even read my post?


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## Bulldog1 (Oct 21, 2011)

480sparky said:


> Uh, so am I.
> 
> Did you even read my post?


That wasn't directed at you 480. It was for wildleg. On my phone. I may have quoted you by mistake.


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## dronai (Apr 11, 2011)

480sparky said:


> And thus is born yet another Urban Legend Electric Code section. Just like _No Wire Nuts in a Panel_, _Raceways Cannot Exceed 100'_, _#12 Wire must Be on a 20a Breaker_, _NM Is Made With THHN_, etc.


I was taught NM is THHN from an inspector, in a code class.

Is there a code reference for no wirenutting in a panel ? I was taught this one also.:blink:


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## wildleg (Apr 12, 2009)

dronai said:


> I was taught NM is THHN from an inspector, in a code class.
> 
> Is there a code reference for no wirenutting in a panel ? I was taught this one also.:blink:


NM may be made with THHN conductors, it may even say so on the spec sheet; but unless the conductors are marked THHN (not very common), they cannot be used as THHN, so you can call them anything you like, but it's pointless.

You can make splices in a panel if it meets the code requirements, and if it is listed for splicing.


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## wildleg (Apr 12, 2009)

Bulldog1 said:


> We are talking about derating. Did you even read the thread?


re-read your own posts. You make it sound like you can use wire at its 90 degree rating.


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## Bulldog1 (Oct 21, 2011)

wildleg said:


> re-read your own posts. You make it sound like you can use wire at its 90 degree rating.


The whole thread is about derating. No one has mentioned ampacity


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## wildleg (Apr 12, 2009)

Bulldog1 said:


> The whole thread is about derating. No one has mentioned ampacity


thank GOD. I thought you were just obstinate, but at least now I know that you just don't know what you are talking about.


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## dronai (Apr 11, 2011)

wildleg said:


> NM may be made with THHN conductors, it may even say so on the spec sheet; but unless the conductors are marked THHN (not very common), they cannot be used as THHN, so you can call them anything you like, but it's pointless.
> 
> You can make splices in a panel if it meets the code requirements, and if it is listed for splicing.


Inspectors in my neck of the woods, will allow one or two splices only in the panels. Looking for a code reference.


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## dronai (Apr 11, 2011)

dronai said:


> Inspectors in my neck of the woods, will allow one or two splices only in the panels. Looking for a code reference.


 
*Found it 312.8 *


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## wildleg (Apr 12, 2009)

Bulldog1 said:


> You are a moron. Everyone but you is talking about derating off 90 degree column.


I just wish you knew what the little numbers in the column represented.(or for that matter, what the "rating" of a conductor is ). Its ok, you'll figure it out.


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## 480sparky (Sep 20, 2007)

dronai said:


> I was taught NM is THHN from an inspector, in a code class.
> 
> Is there a code reference for no wirenutting in a panel ? I was taught this one also.:blink:



You need new instructors.


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## 480sparky (Sep 20, 2007)

dronai said:


> *Found it 312.8 *



_312.8 Enclosures for Switches or Overcurrent Devices.
Enclosures for switches or overcurrent devices shall not be
used as junction boxes, auxiliary gutters, or raceways for conductors
feeding through or tapping off to other switches or
overcurrent devices, unless adequate space for this purpose is
provided. The conductors shall not fill the wiring space at any
cross section to more than 40 percent of the cross-sectional
area of the space, and the conductors, splices, and taps shall
not fill the wiring space at any cross section to more than
75 percent of the cross-sectional area of that space._

Where is "2 splices" listed in there?


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## dronai (Apr 11, 2011)

480sparky said:


> You need new instructors.


 
Looks like I found them here :laughing:


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## dronai (Apr 11, 2011)

480sparky said:


> _312.8 Enclosures for Switches or Overcurrent Devices._
> _Enclosures for switches or overcurrent devices shall not be_
> _used as junction boxes, auxiliary gutters, or raceways for conductors_
> _feeding through or tapping off to other switches or_
> ...


 *That's a City code I guess ?*

312.8 Switch and Overcurrent Device Enclosures, with Splices, Taps, and Feed through Conductors. The wiring space for enclosures for switches or overcurrent devices shall be permitted for conductors feeding through, spliced, or tapping off to other enclosures. Not to exceed 40% of the cross sectional space. That's still a cluster.......


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## Bulldog1 (Oct 21, 2011)

wildleg said:


> I just wish you knew what the little numbers in the column represented.(or for that matter, what the "rating" of a conductor is ). Its ok, you'll figure it out.




I apologize for calling you a moron. I don't believe anyone else got the same impression as you did from my posts. Now if you would take your own advice and go back and read the whole thread you will see I was talking specifically about small conductors. I did not express that as well as I should and Dennis pointed that out. I made a post saying I envisioned the op and a 3/4 emt full of small conductors. Then I made a statement that in the old days most wire was not rated at 90 degrees so derating was almost required anytime more than 3 wires were in a pipe. No where did I say you could base your conductor size off the 90* column. Even first year apprentices usually know the 90* column is for derating. You are at least that right? So I assumed that since the whole thread has been about derating you wouldn't need someone to explain it to ya.


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## 480sparky (Sep 20, 2007)

Derating always starts with T310.16 [or the 2011 version: T310.15(B)(16)].

If it's a 90°C conductor, you derate from the 90°C column. If it's a 75°C conductor, you derate from the 75°C column. If it's a 60°C conductor, you derate from the 60°C column.


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## BBQ (Nov 16, 2010)

Wow, this thread is a train wreck. :laughing:


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## 480sparky (Sep 20, 2007)

BBQ said:


> Wow, this thread is a train wreck. :laughing:


Only if you derate for it. :whistling2:


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## user4818 (Jan 15, 2009)

BBQ said:


> Wow, this thread is a train wreck. :laughing:


:thumbup:


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## farlsincharge (Dec 31, 2010)

The OP is correct as far as Canada is concerned. More than 3 ccc and derating must occur.
People seem to ignore derating, voltage drop, conduit and box fill, whenever it is convenient.
The inspectors are starting to crack down on it and I welcome it.


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## chris856 (Jun 12, 2009)

Bulldog1 said:


> We were talking about small conductors. I posted a comment about small conductors. I don't need to do "research" I know this crap. But I will give you I need to stop being lazy and post complete thoughts so everyone knows what I am trying to say.


 Sorry dude, I wasn't responding to your posts, just the OPs.


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## chris856 (Jun 12, 2009)

480sparky said:


> This 'nine is fine' logic is a classic example of creating 'shortcut' that ends up being misunderstood and wholely misused.
> 
> I think a lot of fledgling electricians manage to stumble across the small-conductor 'Nine Rule' on their own. So over the years, they use this rule-of-thumb instinctively. As the years wax & wane, they end up working with less-knowledgeable noobs, who are off-handedly informed of this wondrous and mysterious 'Nine is Fine' concept.
> 
> ...


 Fair enough response. I in fact do look these things up on my own, but say things like that because so many of peers don't even own a codebook, and go by rules of thumb and what "so and so" told them. Maybe you're right and I shouldn't sink to thier level, but when I actually start making actual code references or trying to explain things logically, they get a blank stare on thier faces then act like I am some kind of nerd actually doesn't know anything. 

There could be an entire thread on "what my journeyman said" and rules of thumb.


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## Bulldog1 (Oct 21, 2011)

chris856 said:


> Sorry dude, I wasn't responding to your posts, just the OPs.



No problem. This thread turned it a cluster before it was even started. I'm also glad you didn't put the smackdown on me. From the looks of your avatar I would get the crap kicked out of me. :laughing:


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## chris856 (Jun 12, 2009)

Bulldog1 said:


> No problem. This thread turned it a cluster before it was even started. I'm also glad you didn't put the smackdown on me. From the looks of your avatar I would get the crap kicked out of me. :laughing:


 Only thing I have in common with the Macho Man is thinning hair.


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