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Ampacity #74523 01/26/07 09:53 AM
Joined: Oct 2006
Posts: 6
R
Rowdy Rudy Offline OP
Junior Member
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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Re: Ampacity #74524 01/26/07 10:58 AM
Joined: Jan 2005
Posts: 5,316
renosteinke Offline
Cat Servant
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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.

Re: Ampacity #74525 01/26/07 02:50 PM
Joined: May 2003
Posts: 2,876
E
e57 Offline
Member
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
Re: Ampacity #74526 01/26/07 03:11 PM
Joined: Jul 2004
Posts: 625
S
SolarPowered Offline
Member
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.

Re: Ampacity #74527 01/26/07 07:07 PM
Joined: Jun 2005
Posts: 821
S
ShockMe77 Offline
Member
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).]

Re: Ampacity #74528 01/26/07 07:11 PM
Joined: Dec 2001
Posts: 2,455
T
Texas_Ranger Offline
Member
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!

Re: Ampacity #74529 01/27/07 09:08 AM
Joined: Aug 2001
Posts: 7,520
P
pauluk Offline
Member
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!

Re: Ampacity #74530 01/27/07 09:10 AM
Joined: Dec 2001
Posts: 2,455
T
Texas_Ranger Offline
Member
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.

Re: Ampacity #74531 01/27/07 11:54 AM
Joined: Mar 2005
Posts: 1,213
S
SteveFehr Offline
Member
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!

Re: Ampacity #74532 01/29/07 10:11 PM
Joined: Mar 2004
Posts: 98
O
OreElect Offline
Member
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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