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#90966 - 12/19/04 05:36 AM NEC Help
AndyP Offline
Member
Registered: 08/11/04
Posts: 20
What is the ampacity of the wire in #11 if it was installed to feed Light poles?

I look in Article 310.16 but I'm just confused.

lol man I'm tired. #11 meaning THHN 8 awg

[This message has been edited by AndyP (edited 12-19-2004).]

[This message has been edited by AndyP (edited 12-19-2004).]
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#90967 - 12/19/04 05:43 AM Re: NEC Help
russ m Offline
Member
Registered: 02/22/03
Posts: 169
Loc: Burbank,IL,USA
"What is the ampacity of the wire in #11 if it was installed to feed Light poles?"

Whats #11 refer to?
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#90968 - 12/19/04 05:56 AM Re: NEC Help
AndyP Offline
Member
Registered: 08/11/04
Posts: 20
Never mind I think it's 55a
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#90969 - 12/19/04 06:09 AM Re: NEC Help
russ m Offline
Member
Registered: 02/22/03
Posts: 169
Loc: Burbank,IL,USA
Generally conductors below 100amp are rated according to the 60degree column of 310.16.

You must rate the wire to the lowest value of any component in the circuit. The degree rating of the breaker, and any devices, lugs, or equipment, have to be taken into concideration.

8 copper = 40amps for 3 or less conductors.
You have to derate if you have more than three conductors or have ambient temperatures greater than 86 degrees F.

To derate the wire use the 90 degree column if using thhn/thwn.

[This message has been edited by russ m (edited 12-19-2004).]
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#90970 - 12/19/04 06:15 AM Re: NEC Help
russ m Offline
Member
Registered: 02/22/03
Posts: 169
Loc: Burbank,IL,USA
while you may use the 90 degree column for derating, (use what ever column the wire is rated for) you still have to use the lower of the two values for your conductor ampacity. Meaning the the lower of the two, (1)60 degree column or (2)the derated 90 degree wire.

[This message has been edited by russ m (edited 12-19-2004).]
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#90971 - 12/19/04 06:19 AM Re: NEC Help
AndyP Offline
Member
Registered: 08/11/04
Posts: 20
Thanks
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#90972 - 12/19/04 06:19 AM Re: NEC Help
iwire Offline
Moderator
Registered: 01/05/03
Posts: 4391
Loc: North Attleboro, MA USA
Andy it is very unlikely you can use the 90 C column which lists 8 AWG @ 55 amps.

You may very well be able to use the 75 C column if the terminations you are using are rated 75 C. At 75 C 8 AWG CU is rated 50 amps.
_________________________
Bob Badger
Construction & Maintenance Electrician
Massachusetts
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#90973 - 12/19/04 06:28 AM Re: NEC Help
russ m Offline
Member
Registered: 02/22/03
Posts: 169
Loc: Burbank,IL,USA
It might be helpfull for you to look at article 110.14(C)

I had to edit the article number

[This message has been edited by russ m (edited 12-19-2004).]

[This message has been edited by russ m (edited 12-19-2004).]
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