Understanding national electrical code volume1

[Callaway]

Could someone sum up for me what 110.14(c)(1) is saying? Not getting it. This is from page 148 in Understanding .....volume 1. How do you choose terminal temperature if not given as in question 220-27? Are ranges continuous loads? Why is 110.14c1 mentioned in the answer?

 

[augie47]

I don't have the document you are referencing but 110.14(C) is basically telling you that you have to take the temperature rating of the device at terminations into account when selecting conductor ampacities.
For an example, a #10 THWN-2 will have an ampacity of 40 amps in the 90°C column, however, if it is operated at that current the heat that the conductor generates would damage devices rated at a less temperature, so the termination temperature ratings much be taken into account. In the case of the #10, if you were terminating on devices rated at 60°C, your conductor final allowed ampacity would be 30 amps.
Since conduit fill and ambient only effect the insulation, you can use the 90° ampacity in derating.

 

[Martin B]

Is this article section telling us that when a terminal is not marked with a temp. rating ( or the question does not give you one ) that we should assume it to be 60 Deg. ? And size our wire based on the 60 Deg. Column Table 310.14 (B)?

75 Deg. When over 100 amp and size 1 AWG.

 

[Smart $]

...
Since conduit fill and ambient only effect the insulation, you can use the 90° ampacity in derating.

The circuit ampacity is thus limited to the smaller of the two determinations, i.e 110.14(C) terminal temperature limitation ampacity and 310.15 conductor [condition of use] allowed ampacity.

 

[Callaway]

Thanks

Thanks

The circuit ampacity is thus limited to the smaller of the two determinations, i.e 110.14(C) terminal temperature limitation ampacity and 310.15 conductor [condition of use] allowed ampacity.

thanks

 

[Callaway]

Practice questions in understanding nec volume 1 by mike holt

Practice questions in understanding nec volume 1 by mike holt

I am continually getting the wrong wire size for practice questions and can't figure out why. Pages 148-153 mainly. There is usually a reference with the book's answer but it never seems to be an explanation to me of why the wire size is what it is. I think there must be several factors that aren't mentioned?

 

[Smart $]

I am continually getting the wrong wire size for practice questions and can't figure out why. Pages 148-153 mainly. There is usually a reference with the book's answer but it never seems to be an explanation to me of why the wire size is what it is. I think there must be several factors that aren't mentioned?

Can't help... I don't have the book, and you didn't provide enough info even if I did.