Wire temperature limitations

[lexkyphil]

I need some help finding the Code reference that tells us even if we are using a THWN 90 deg C wire, its rating is limited by the temperature of the termination device rating-typically, 75 deg C. Help! Thanks / Phil

 

[chris kennedy]

I need some help finding the Code reference that tells us even if we are using a THWN 90 deg C wire, its rating is limited by the temperature of the termination device rating-typically, 75 deg C. Help! Thanks / Phil

No book here so I'm guessing 110.14(C).

 

[ronmath]

Chris is right, if you have the handbook, look also at 310.10. The conductor ratings are not the problem, it is the rating of the terminations. They must also be rated at 90C for you to use the 90C rating of the conductors. You can however use the higher 90C rating when considering derating wires due to fill, ambient temperature etc. Hope this helped.

 

[charlie b]

No book here so I'm guessing 110.14(C).

That is correct.

 

[charlie b]

You can however use the higher 90C rating when considering derating wires due to fill, ambient temperature etc.

That, too, is provided by 110.14(C). Check out the second sentence of that article.