Overhead Service wire sized from 90 c or 75 c table ?

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Gary11734

Senior Member
Location
Florida
This is a wet location so the-2 conductor can be sized according to it's 90° C ampacity.

I looked. You are correct. Thanks for pointing me in the right direction!

The only time -2 has to go back to 75 degrees is if it's in contact with oil.

From Southwire;

THWN-2- Wet or dry locations not to exceed 90° C or locations not to exceed 75° C when exposedto oil
 

infinity

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New Jersey
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Journeyman Electrician
I looked. You are correct. Thanks for pointing me in the right direction!

The only time -2 has to go back to 75 degrees is if it's in contact with oil.

From Southwire;

THWN-2- Wet or dry locations not to exceed 90° C or locations not to exceed 75° C when exposed to oil

Good to know. Encore has similar data sheet:

Applications:
Type THHN/THWN-2 building wire is intended for general purpose applications as defined by the National Electrical Code (NEC).
Type THHN/THWN-2 is permitted for new construction or rewiring for 600-volt applications. Applications requiring Type THHN
or THWN-2: the conductor is appropriate for use in wet or dry locations at temperatures not to exceed 90°C or not to exceed
75°C in oil or coolants
. Applications requiring Type MTW: the conductor is appropriate for use in dry locations at 90°C, or
not to exceed 60°C in wet locations or where exposed to oils or coolants. Applications requiring Type AWM: the conductor is
appropriate for use at temperatures to not exceed 105°C in dry locations.

I wonder if this is addressed in the NEC?
 
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