# Temperature Column ?



## mjjg92 (Jan 19, 2012)

I mostly due residental work ,so I'm always trying to figure this out. Any help would be appreciated. 
I am installing a 200 amp single phase service at a commercial building.Conductors to be run from the Utility drop to the Meter Pan in either PVC or EMT conduit. I wanted to run 3/0 thhn/thwn , but now I' m not sure. 
Do I have to use the 60 degree C column or can I use the 75 degree column ?
Conductors are to be Copper
Thanks for any input.


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## BBQ (Nov 16, 2010)

You can use the 75C column for pipe and wire.

NM and at times SE is limited to 60C.


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## mbednarik (Oct 10, 2011)

All of the PVC i have seen has a 90C rating. Any of the metal conduits i don't think you have to worry about. I have seen some sealtight with only a 60C rating though. You can go a hot as your coldest rating, example if you are pulling THWN-2 wire (90C) in PVC conduit which carries a 90C rating, but your breakers lug rating is 60/75, you can only run the wire at 75C. Now if you had the same run and added a piece of sealtight to flex into some equipment, and your sealtight carried a 60C rating, you can only run the wire to 60C.


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## therain (Jan 18, 2013)

*new member*

See art.110.14 (C) (1)


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## mjjg92 (Jan 19, 2012)

was looking for the wire size temperature rating not the conduit temp rating . but thanks.


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## buddhakii (Jan 13, 2011)

mbednarik said:


> All of the PVC i have seen has a 90C rating. Any of the metal conduits i don't think you have to worry about. I have seen some sealtight with only a 60C rating though. You can go a hot as your coldest rating, example if you are pulling THWN-2 wire (90C) in PVC conduit which carries a 90C rating, but your breakers lug rating is 60/75, you can only run the wire at 75C. Now if you had the same run and added a piece of sealtight to flex into some equipment, and your sealtight carried a 60C rating, you can only run the wire to 60C.


Never knew conduit had a temp. rating. :no:


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## mbednarik (Oct 10, 2011)

So you never use carflex, sealtight, ENT or PVC conduit? Look at this. :yes:
http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet234


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## therain (Jan 18, 2013)

3/0 conductors per 110.14 (C) (1) (b) 75 deg. Column for. 
circuits over 100A or larger than 1AWG


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## Bulldog (Jan 28, 2009)

mbednarik said:


> All of the PVC i have seen has a 90C rating. Any of the metal conduits i don't think you have to worry about. I have seen some sealtight with only a 60C rating though. You can go a hot as your coldest rating, example if you are pulling THWN-2 wire (90C) in PVC conduit which carries a 90C rating, but your breakers lug rating is 60/75, you can only run the wire at 75C. Now if you had the same run and added a piece of sealtight to flex into some equipment, and your sealtight carried a 60C rating, you can only run the wire to 60C.


That temperture listed is only for temperature of the enviroment that the sealtight can be used.

Wire ampacity is based on the temperture ratings of the terminals and number of wires in the conduit.
So if the terminal is rayed 75 degree than use 75 degree column and use 60 degree column for 60 degree terminal, etc. The 90 degree column can be used for derating.


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## mbednarik (Oct 10, 2011)

So you think you can have something hotter on the inside of the pipe but not on the outside. If the pipe can't candle the temp, it can't handle it.


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## Dennis Alwon (May 9, 2009)

mbednarik said:


> So you think you can have something hotter on the inside of the pipe but not on the outside. If the pipe can't candle the temp, it can't handle it.


Not sure I agree with that. The temp of the wire does not necessarily mean that the temp. of the conduit is the same. For instance an underground pvc is being heated by the earth. Perhaps in direct sunlight it may be an issue but in the op's question I think it is fine. Besides that is metal conduit that is not used in the op's question.


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