# Hey Romex guys



## 480sparky (Sep 20, 2007)

http://www.electriciantalk.com/f2/nm-question-9159/#post126148


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## NolaTigaBait (Oct 19, 2008)

I thought yes, as long as the load isn't more than 55 amps. Is this a trick question?


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## Chris Kennedy (Nov 19, 2007)

NolaTigaBait said:


> Is this a trick question?


No, just redundant.


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## John Valdes (May 17, 2007)

Chris Kennedy said:


> No, just redundant.


Chris, I have not seen this question before. I guess you want me to do a search, right?
No, this is not a trick question.

I just poured over both articles and still have no concrete answer.


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## Chris Kennedy (Nov 19, 2007)

John Valdes said:


> Chris, I have not seen this question before. I guess you want me to do a search, right?
> No, this is not a trick question.
> 
> I just poured over both articles and still have no concrete answer.


Yeah, as I said, looks good to me. That LSU fan seems to agree.

LSU-Georgia 3:30pm

Miami-Oklahoma 8:00pm


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## walkerj (May 13, 2007)

This LSU fan also agrees


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## Magnettica (Jan 23, 2007)

Seems ok to me. 

It's the guys who install 4-3 NM with 100 amp protection who are off their rockers.


How bout these Islanders eh?


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## Decepticon (Oct 4, 2009)

I noticed that the sub panel in my 19060's built condo is fed with 8-3 NM, yet the disconnect down in the boiler room is a 2 pole 50A breaker. Some units in the building have 50A breakers while others have 40A, although they all use 8-3 Romex. I don't know if people upgraded the breakers themselves, cause I thought 40A was max with 8AWG when it's Romex?


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## mikeg_05 (Jan 1, 2009)

Magnettica said:


> Seems ok to me.
> 
> It's the guys who install 4-3 NM with 100 amp protection who are off their rockers.
> 
> ...


For sure, I told my boss it was only rated for 70 amps and he looked at me like I was from mars. I guess he was too lazy to order a two pole seventy.:blink:


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## JohnJ0906 (Jan 22, 2007)

Decepticon said:


> I noticed that the sub panel in my 19060's built condo is fed with 8-3 NM, yet the disconnect down in the boiler room is a 2 pole 50A breaker. Some units in the building have 50A breakers while others have 40A, although they all use 8-3 Romex. I don't know if people upgraded the breakers themselves, cause I thought 40A was max with 8AWG when it's Romex?


That could have been legal at the time, but my NECs don't go that far back - Cue for Ken........


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## wingz (Mar 21, 2009)

Chris Kennedy said:


> Can a 6-3 NM for a panel feeder be protected by a 60A breaker. 334.80 and 240.4?


You have to satisfy 215.2(A)(1), before you apply 240.4(B).


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## Magnettica (Jan 23, 2007)

mikeg_05 said:


> For sure, I told my boss it was only rated for 70 amps and he looked at me like I was from mars. I guess he was too lazy to order a two pole seventy.:blink:


They're just not very common, as in you actually have to look for them on the truck and that's only if they're there to begin with!


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## GEORGE D (Apr 2, 2009)

what about 334.80?


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## Decepticon (Oct 4, 2009)

JohnJ0906 said:


> That could have been legal at the time, but my NECs don't go that far back - Cue for Ken........


The breakers seem pretty new compared to the 40 ampers.


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## 480sparky (Sep 20, 2007)

JohnJ0906 said:


> That could have been legal at the time, but my NECs don't go that far back - Cue for Ken........


There's no reference to ampacity for NM in the 60's. The word 'ampacity' wasn't used in the NM Section until 336-26 of the 1999.


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## B4T (Feb 10, 2009)

480sparky said:


> There's no reference to ampacity for NM in the 60's. The word 'ampacity' wasn't used in the NM Section until 336-26 of the 1999.


Makes you wonder why they lowered the ampacity for NM

I have seen plenty of sub - panels wired with 4/3 NM that ran to the disco next to the MP

THHN is rated for 100 amp for single family dwellings

The wire in NM is THHN correct??


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## 480sparky (Sep 20, 2007)

Black4Truck said:


> Makes you wonder why they lowered the ampacity for NM


Not sure they ever really lowered it. More like the finally addressed it.



Black4Truck said:


> The wire in NM is THHN correct??


Prove that and you'll be the ET Man of the Year.


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## NolaTigaBait (Oct 19, 2008)

I heard it was thhn. I looked at southwire's site and all it says is that they are 90 degree conductors. I've used 4-3 nm for 100 amp feeders. If it has 90 degree conductors, I think it should be ok to use 310.15b6 for this.


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## 480sparky (Sep 20, 2007)

NolaTigaBait said:


> I heard it was thhn. I looked at southwire's site and all it says is that they are 90 degree conductors. I've used 4-3 nm for 100 amp feeders. If it has 90 degree conductors, I think it should be ok to use 310.15b6 for this.


They are not THHN. They are simply 90°C insulation conductors. 334.112.


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## B4T (Feb 10, 2009)

GEORGE D said:


> what about 334.80?


334.80 tells you to use 60 degree column on 310.15 

Only problem is there is no chart titled 310.15 

I asked the Forum Historian (Ken.. AKA TOOL) and he directed me to 310.16

Could it be the CMP screwed up and gave us wrong information :no:


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## chris856 (Jun 12, 2009)

The 90 degree column is for bundling only. You won't find any terminals rated higher than 75 degrees so you can't put anything bigger than an 90 amp breaker in with 4-3.


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## user4818 (Jan 15, 2009)

Romex is totally dangerous and should be permanently banned as a wiring method.


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## william1978 (Sep 21, 2008)

Peter D said:


> Romex is totally dangerous and should be permanently banned as a wiring method.


 Wait a minute romex is your bread and butter right?:thumbup:


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## NolaTigaBait (Oct 19, 2008)

chris856 said:


> The 90 degree column is for bundling only. You won't find any terminals rated higher than 75 degrees so you can't put anything bigger than an 90 amp breaker in with 4-3.


Where are you getting 90 amps?....Its either the 60 degree chart or 310.15b6. I think it is ok to use 4-3nm under the 310.15b6 chart(it is accepted here). Yes, I know they are not thhn, i've heard people say that it was.


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## B4T (Feb 10, 2009)

I read it as 70 amp breaker max for 4/3 NM

THAT really sucks!!!!


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## 480sparky (Sep 20, 2007)

william1978 said:


> Wait a minute romex is your bread and butter right?:thumbup:


Peter deosn't use romex, he uses SO and lamp cord.:laughing:


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## user4818 (Jan 15, 2009)

480sparky said:


> Peter deosn't use romex, he uses SO and lamp cord.:laughing:


I stopped using that too. I now use telephone wire and Cat 5 for everything.


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## B4T (Feb 10, 2009)

Anyone hear of a "ser" cable that is like NM, but service entrance rated and would allow #4 to be put on 100 amp breaker


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## NolaTigaBait (Oct 19, 2008)

Black4Truck said:


> Anyone hear of a "ser" cable that is like NM, but service entrance rated and would allow #4 to be put on 100 amp breaker


I thought you use ser and seu on the 60 degree column as well. I think nm or ser is ok to use as a feeder.


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## B4T (Feb 10, 2009)

NolaTigaBait said:


> I thought you use ser and seu on the 60 degree column as well. I think nm or ser is ok to use as a feeder.


#4 SE works for 100 amp, but the 4/wire cable is the problem for sub panels

Why I was interested in the "SER" rated cable


*
Table 310.15(B)(6) Conductor Types and Sizes for
120/240-Volt, 3-Wire, Single-Phase Dwelling Services and
Feeders. Conductor Types RHH, RHW, RHW-2, THHN,
THHW, THW, THW-2, THWN, THWN-2, XHHW,​XHHW-2, SE, USE, USE-2
*


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## NolaTigaBait (Oct 19, 2008)

I would think that SER would fall into that category.


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## manchestersparky (Mar 25, 2007)

480sparky said:


> There's no reference to ampacity for NM in the 60's. The word 'ampacity' wasn't used in the NM Section until 336-26 of the *1999*.




The word ampacity is used in the* 1987* NEC section 326-26
" conductors shall be rated at 90 degree ( 194 F). The ampacity of types NM and NMC cable shall be that of 60 degree( 140 F) conductors and shall comply with section 310-15."

The 1987 is the oldest NEC I have at home. 
(# 6 NM Cable is rated for 55 amp at 60 degree in the '87)


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## 480sparky (Sep 20, 2007)

I guess I was looking for a specific paragraph titled Ampacity.

The language you mention began in the 1975.


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## JohnJ0906 (Jan 22, 2007)

chris856 said:


> The 90 degree column is for bundling only. You won't find any terminals rated higher than 75 degrees so you can't put anything bigger than an 90 amp breaker in with 4-3.


You can derate from the 90 degree column. However, the final result cannot exceed the 60 degree column. See 334.80.
4-3 CU romex is a 70 amp conductor, regardless if the terminal is rated 75 deg or 60.


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## electures (Oct 23, 2008)

*Yes, it is permissible.*

I presented this question to my first & fourth year h/s electrical class. They agree that 6/3 NM cable used as a feeder can be protected by a 60A breaker provided the calculated load does not exceed 55A's.

Penn-Tech all day!!

:thumbsup:


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