# Articles 110.14 and 240.4



## NoCoSparky (Mar 3, 2012)

I'll make it simple:

Article 110.14(C)(1)(a)(1) limits wire ampacity to no more than it's termination ratings. Result: #6 THHN is only good for 65 amps if your breaker is rated at 60 deg or 75 deg, as mine is, no more (table 310.15(B)(16), 75 deg column).

Article 240.4(B) says that if the ampacity of wire (rated 800 amps or less) does not match a standard breaker size, you can go up to the next size breaker, which would mean you could protect #6 THHN at 70 amps. 

Which of the two should an electrician choose? Which is correct? Am I missing something?


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## HARRY304E (Sep 15, 2010)

NoCoSparky said:


> I'll make it simple:
> 
> Article 110.14(C)(1)(a)(1) limits wire ampacity to no more than it's termination ratings. Result: #6 THHN is only good for 65 amps if your breaker is rated at 60 deg or 75 deg, as mine is, no more (table 310.15(B)(16), 75 deg column).
> 
> ...


If I understand your question the answer is 70 amp breaker..


Welcome to the forum..:thumbup:


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## hardworkingstiff (Jan 22, 2007)

HARRY304E said:


> If I understand your question the answer is 70 amp breaker..


Provided the load is not more than 65-amps.


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## hardworkingstiff (Jan 22, 2007)

NoCoSparky said:


> Am I missing something?


Nope, and this is something a lot of electricians are not aware of and do not care about.


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## BBQ (Nov 16, 2010)

NoCoSparky said:


> I'll make it simple:
> 
> Article 110.14(C)(1)(a)(1) limits wire ampacity to no more than it's termination ratings. Result: #6 THHN is only good for 65 amps if your breaker is rated at 60 deg or 75 deg, as mine is, no more (table 310.15(B)(16), 75 deg column).
> 
> ...


You can never connect more load to a conductor than it is rated.

All 240.4(B) allows is moving up to the next breaker size in some cases.


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## chicken steve (Mar 22, 2011)

aren't we in the 60C col under 100A ?

~CS~


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## hardworkingstiff (Jan 22, 2007)

chicken steve said:


> aren't we in the 60C col under 100A ?
> 
> ~CS~


Not if the termination points are listed for 75c. Most all termination points are now rated for 75c


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## don_resqcapt19 (Jul 18, 2010)

Article 240 has to do with the protection of the conductor. Nothing in Article 240 changes the ampacity of a conductor.


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## NoCoSparky (Mar 3, 2012)

BBQ said:


> You can never connect more load to a conductor than it is rated.
> 
> All 240.4(B) allows is moving up to the next breaker size in some cases.


In which cases?


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## NoCoSparky (Mar 3, 2012)

In this case, the machine is rated at 62 amps. It seems that it could be argued either way, that a 70 amp breaker is ok on #6 THHN or that the wire must be sized #4 THHN. But if the place burns down, I don't want it to be because I used a 70 amp breaker on #6 wire.

Another question: aren't we supposed to load a circuit to no more than 80% of it's rating? Perhaps I am wrong about that.


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