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Free Air #84860
05/13/03 02:22 PM
05/13/03 02:22 PM
B
boxford  Offline OP
Member
Joined: Mar 2003
Posts: 15
St. Paul, MN, USA
Referencing Table 310.19 it states the following:

Table 310.19 Allowable Ampacities of Single-Insulated Conductors, Rated 0 Through 2000 Volts, 150 degrees Through 250 degrees (302 degrees F Through 482 degrees F), in Free Air, Based on Ambient Air Temperature of 40 degrees C (140 degrees F)

Does anyone know of a reference that specifically states the definition of "Free Air"?

I appreciate anyones help.
Brian

2017 / 2014 NEC & Related Books and Study Guides
Re: Free Air #84861
05/13/03 05:26 PM
05/13/03 05:26 PM
HotLine1  Offline

Member
Joined: Apr 2002
Posts: 6,918
Brick, NJ USA
Boxford:
I'll take a stab at "free air"...
The best street definition I can come up with is an installation as the utility companies use. Single conductors mounted on cross arms or similar approved methods on poles. I could take it a step further and mention the "older" rack service drops at some commercial buildings; a "rack" is mounted to the exterior wall, on which insulators are mounted, and individual conductors are mounted to the insulators. This is not a commonly used installation now.
Hope this helps
John


John
Re: Free Air #84862
05/13/03 06:05 PM
05/13/03 06:05 PM
E
electric-ed  Offline
Member
Joined: Jul 2002
Posts: 175
Canada
Single conductors, spaced more than one diameter apart in a ventilated (ladder type) cable tray, are usually considered to be "free air".

Ed

Re: Free Air #84863
05/13/03 07:06 PM
05/13/03 07:06 PM
S
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,344
and i thought i could fill my tires for free here, so much for livin' in the past eh? [Linked Image]

Re: Free Air #84864
05/14/03 07:52 AM
05/14/03 07:52 AM
B
boxford  Offline OP
Member
Joined: Mar 2003
Posts: 15
St. Paul, MN, USA
I really appreciate everyones help.

Brian


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