how much current can AWG wire handle

Hello,
Does anyone know where I can find out how much current specific gauges of wire can handle? I've looked up web pages on it, but can't figure
out what they mean... for example at
http://www.interfacebus.com/Copper_Wire_AWG_SIze.html
There's a column that says: Current Carrying, and another that says Fusing Current
I'm interested in figuring out if 20 AWG wire can handle steady DC of 7.25 Amps, for 20 AWG is says Current Carrying: 1.46 Fusing Current: 58.4
? I don't get what they're saying.... other websites have been similarly confusing..
Much Thanks
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www.rstengineering.com then Jim's Engineering Page, then Wire Table.

# 20 wire can carry any current you like, up to the fusing current. It is all a matter of how hot you are willing to let the wire get. The referenced table above will let you calculate the temperature rise of a wire over ambient for any arbitrary current and gauge.

The Current Carrying is how much current the wire can handle for a given rise in temperature over ambient. There should also be a note that the temperature rise will be more than calculated if the wires are in a bundle together. An unbundled #20 wire at 7.5 amps will rise about 30F (15C) over ambient, which is pretty warm. Your call.
Fusing current is the current at which the wire will melt.
Jim
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The current carrying capacity in the listed table is based on 700 circular mills per amp, a very conservative number for wire wound inside a transformer where heating is an issue.
The National electric code specifies current carrying capacity for open wires or house wiring for example about twice that or 300 to 350 circular mills per amp. This gives 20 AWG wire about a 3 Amp rating.
What is your application? What is the duty cycle? What is the thermal environment, how hot can it get? Is it in a transformer or in open air and how insulated? How much voltage drop can you tolerate?
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panfilero wrote:

Back in the day, the usual rule of thumb for low-frequency power transformers in continuous use was 1000 circular mils per amp, where a 'circular mil' is the square of the diameter in mils (thousandths of an inch), i.e. 1 circular mil = (pi/4) square mil. The 1000 circular mils per amp rule comes out to 5.07e-6 square metres per amp.
Cheers,
Phil Hobbs
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But before the wire gets too hot, there will probably be so much voltage drop that the voltage at the load is too low, so that might be the more important criterion.
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On Mon, 08 Dec 2008 17:06:55 -0000, Phil Hobbs

Mil is confusing. A lot of folk in metric countries say "mil" short for millimetre. A metre is considerably different to an inch.
P.S., what's a click?
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wrote:

No, we don't. We usually say mm. Rough comparison: #10->10 mm^2 , 35 A fuse for main residence #12->6 mm^2, 25 A for stove #14->4 mm^2, 20 A water heater #16->2.5 mm^2, 16 Awashing machine, dishwasher #18->1.5 mm^2, 10 A lighting These figures are for one live conductor in a conduit inside the wall.

When I was in Rhodes (east Greece), we were camping with my 542nd mechanized infantry battalion, and there were lots of scorpions. We had brought a wooden bank with us, and at bed time I saw a sergeant laying to sleep on the bench. I asked, 'Is sir something wrong, I could help' he said just leave me alone. I learnt from his colleagues that he found a scorpion under his pillow (in his tent) and the "brave" sergeant decided to sleep on the bench. Soldiers wished to be bitten, so that they could get sick leave.
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wrote:

Designers in the UK doing technical drawing often say "400 mils" to mean 400mm. Just in speach though, it is written as mm.
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Common speak in the workshop too.
--
Stuart Winsor

For Barn dances and folk evenings in the Coventry and Warwickshire area
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"panfilero"

** This page say 20AWG is good for 11 amps when used for "chassis wiring" or wires mounted in mid air.
http://www.powerstream.com/Wire_Size.htm
Tallies with my experience.
1 metre of 20AWG will dissipate about 6 watts at 11 amps when used this way.
..... Phil
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On Tue, 9 Dec 2008 09:58:11 +1100, "Phil Allison"

AC 43.13-1B shows AWG 20 okay for about 16.5A if you don't mind 80C rise (eg. very high temperature rated insulation in moderate ambient).
That's for *one wire in free air*, deratings for bundles (two wires are a bundle), and altitude, of course, and the detailed calculations are shown for various situations. May be available on the FAA dot GOV website.
Mostly you'll not want to get anywhere near those current levels or voltage drop will kill you.
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On Mon, 08 Dec 2008 23:21:44 -0000, Spehro Pefhany

How can a voltage drop kill someone? The lower the voltage at the outlet, the safer it is!
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Peter Hucker wrote:

Idiot.
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On Tue, 09 Dec 2008 18:42:38 -0000, Michael A. Terrell

[to group] Could someone buy Michael a sense of humour?
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Peter Hucker wrote:

I have sense of humor, and a deep disdain for the brain dead who continue posting on USENET.
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On Tue, 09 Dec 2008 19:07:52 -0000, Michael A. Terrell

What you meant to say is you're a pompous ass and don't like what anyone else has to say.
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Peter Hucker wrote:

OK, if that thought is what it takes to make you feel like a man. You constantly post misinformation that can cause problems, or cost someone their life. In my book, you are a pathetic fool.
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On Tue, 09 Dec 2008 19:44:14 -0000, Michael A. Terrell

Quote some of this alledged "misinformation".
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Peter Hucker wrote:

That would be almost everything you've ever posted.
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On Tue, 09 Dec 2008 20:06:39 -0000, Michael A. Terrell

Thought so, you have nothing.
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