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#74523 - 01/26/07 09:53 AM Ampacity  
Rowdy Rudy  Offline
Junior Member
Joined: Oct 2006
Posts: 6
Had lunch yesterday with a contractor who had just returned from 2 years in Korea building military facilities. Some things surprising , such as #14 rated @ 30A., #12 @ 40A. & #10 @ 54A. These ratings are based on AWG.
Rowdy


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#74524 - 01/26/07 10:58 AM Re: Ampacity  
renosteinke  Offline
Cat Servant
Member
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
I can't speak for Korea, but the USA is almost unique in it's particular wiring practices. As such, one really has to "leave the USA behind" when leaving the borders.

The ampacity tables are, simply put, our best judgment call. One can always make a case for a higher, or lower, number. It's not at all surprising that different places have slight differences in opinion.

Code issues are not the only places where countries differ. Local construction methods, and lifestyle, have a great effect.


#74525 - 01/26/07 02:50 PM Re: Ampacity  
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
Military and Federal facilities are not under the NEC for the most part, but only guided by industry standards - depending on contract. (This one not being 'standard' for this country....) You also don't mention the insulation - they might be using silicone - which has a much higher temp rating.


Mark Heller
"Well - I oughta....." -Jackie Gleason

#74526 - 01/26/07 03:11 PM Re: Ampacity  
SolarPowered  Offline
Member
Joined: Jul 2004
Posts: 625
Palo Alto, CA, USA
Right out of our own NEC, #14 THHN is rated at 25A, #12 @ 30A, and #10 @ 40A. It is only the hyperconservative limits of 240.4(D) that make our normal limits so much lower.

Even these restrictions do not entirely prevent fires from overloaded branch circuits. But they do manage to do a pretty good job of it.


#74527 - 01/26/07 07:07 PM Re: Ampacity  
ShockMe77  Offline
Member
Joined: Jun 2005
Posts: 821
Rahway, New Jersey
I thought #14 AWG was only rated at 25 amps for derating purposes. That rating is in the 90ยบ column. My understandng is that #14 is good for 20 amps but in only in applications described in 240.4 (G).

[This message has been edited by ShockMe77 (edited 01-26-2007).]

[This message has been edited by ShockMe77 (edited 01-26-2007).]

[This message has been edited by ShockMe77 (edited 01-26-2007).]


#74528 - 01/26/07 07:11 PM Re: Ampacity  
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,400
Vienna, Austria
30A for #14 sounds real heavy!
2.5mm2 is larger than #14 and has an absolute maximum rating of 26A in free air, 25 degrees Celsius ambient temp. So considering #14 is smaller AND Korea most likely has a higher ambient temperature... scary!


#74529 - 01/27/07 09:08 AM Re: Ampacity  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Quote
2.5mm2 is larger than #14 and has an absolute maximum rating of 26A in free air, 25 degrees Celsius ambient temp.


2.5 is rated 30A absolute max. here, free air, 2-core cable, same ambient/conductor temperatures. Clipped direct to a surface it's still 27A.

Which just goes to show how little agreement there is!


#74530 - 01/27/07 09:10 AM Re: Ampacity  
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,400
Vienna, Austria
Quote
Which just goes to show how little agreement there is!

Definitely!
By the way, in general purpose installs said 2.5mm2 is usually protected by a 16A breaker or fuse... so there's another difference between max. rating and real life.


#74531 - 01/27/07 11:54 AM Re: Ampacity  
SteveFehr  Offline
Member
Joined: Mar 2005
Posts: 1,208
Chesapeake, VA
Quote
Military and Federal facilities are not under the NEC for the most part, but only guided by industry standards - depending on contract. (This one not being 'standard' for this country....) You also don't mention the insulation - they might be using silicone - which has a much higher temp rating.
The US military has adopted the NEC for facilities in lieu of older MIL-SPECs and other codes that are just easier to use existing industry standards for. Anything built on a US base *should* be conforming to NEC and a number of other MIL-HDBKs that often exceed NEC requirements. We have much wider authority for deviation then in the civilian sector, though, as a single entity is generally responsible for funding, building and approving a project and isn't always as heavy-handed as a city inspector when it comes to failing things for non-compliance!


#74532 - 01/29/07 10:11 PM Re: Ampacity  
OreElect  Offline
Member
Joined: Mar 2004
Posts: 98
Salem,Oregon.USA
I think in Mexico its ok to use #14 for a 200 amp service as long as you use white pipe.


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