The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Calling all Non-US members!! (Non-US only)
by aussie240
Today at 02:39 AM
Photo Upload Tutorial
by DanK
Yesterday at 11:35 PM
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 9
Texas_Ranger 8
sparkyinak 7
Trumpy 6
Who's Online
2 registered (Radar, LongRunner), 224 Guests and 6 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#214531 - 12/18/14 07:28 PM derating rooftop conductors
BigB Offline
Member

Registered: 03/31/04
Posts: 727
Loc: Tucson, AZ USA
When derating THWN-2 copper conductors for ambient that will eventually terminate in a sub panel with a 125 amp rating can I use the 90C column?

Top
2014 / 2011 NEC & Related Books and Study Guides
#214533 - 12/19/14 12:54 AM Re: derating rooftop conductors [Re: BigB]
Tesla Offline
Member

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
The sole and only reason for that column IS derating.

For there are no 90 degree rated devices out there.

One then uses the lesser computed ampacity limit.

So, yes, you start with the 90 degree column.
_________________________
Tesla

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals