# NEC 110.14 (C) (1)(a)(1)



## EEpowerOK (Sep 12, 2013)

Says 60C column should be used for any amps less than 100 or 1-14 AWG conductors when using 310.15 (B)(16)

I've never seen this before,


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## iahim (Sep 12, 2013)

Correct, but if the problem states that the terminals are rated for 75C, I think you can use the 75C column.


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## EEpowerOK (Sep 12, 2013)

Makes a lot of practice tests questions wrong. CI V3-31 for one.


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## iahim (Sep 12, 2013)

I don't have the current CI exams, so the problem may be different in my version. Are you referring to the the problem with the two single phase 500V motors? If you are, I think there are several issues with that problem. First, I don't think 500V, single phase motors exist. If they do exist, they are not covered in the code. In the solution they pull the FLA from the DC motors table. The problem clearly states single phase, so it is not DC. They even mention that the motors are connected to a transformer.


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## EEpowerOK (Sep 13, 2013)

That's the one, the temp rating should be dropped to 60C since their less than 100 amps.


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## iahim (Sep 14, 2013)

You are correct. Even if the problem states that the conductors are rated 90C, you never use the 90C ampacity to size the conductors, because the terminals of the equipment you are connecting to are never rated 90C. They are only rated 60C (for equipment 100A or less, with some exceptions) or 75C (over 100A). The 90C ampacity is applicable only if you have to derate the conductors for temperature or for more than 3 conductors in the raceway.


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## knight1fox3 (Sep 14, 2013)

In the nuclear industry, you can get 90C rated terminals. I've had to spec them on various projects. But generally you are correct, most of them are 75C. And it's crazy to see almost all applications engineers sizing all conductors to 90C with standard terms.


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## ventilator (Sep 17, 2013)

I believe there is an exception to that piece of code (don't have my book with me) that if the termination points are listed as being rated for a higher temperature you don't have to use the 60degC, you can use the rated temp. I can't think of anything I've used that didn't have dual rated terminations (60/75 deg) but I also work in industrial plants so everything tends to be rated higher than commercial or residential type stuff.\



knight1fox3 said:


> In the nuclear industry, you can get 90C rated terminals. I've had to spec them on various projects. But generally you are correct, most of them are 75C. And it's crazy to see almost all applications engineers sizing all conductors to 90C with standard terms.


I actually had another PE tell me that "the temp rating of the terminations doesn't apply because we are derating based on the 90deg column". When I asked him to explain himself he just got belligerent and wouldn't provide any reasoning other than he shouldn't have to explain himself.


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## knight1fox3 (Sep 17, 2013)

ventilator said:


> knight1fox3 said:
> 
> 
> > In the nuclear industry, you can get 90C rated terminals. I've had to spec them on various projects. But generally you are correct, most of them are 75C. And it's crazy to see almost all applications engineers sizing all conductors to 90C with standard terms.
> ...


I've had similar conversations only they usually try to change the subject and focus on a different problem. When I would bring it back to they, often I would get the, "well that's way we've been doing it" response.


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