Talk:American wire gauge/Archive 1

Archive 1

Bizarre term 'ampacity'

I do not understand the word 'ampacity'. I investigated further and found that it meant current. I changed the word but it was changed back with the comment that it was the word used. Even if it is used in the technical documentation for specialists, is there a way in which we can make the article more accessible to readers? Bobblewik  (talk) 11:06, 22 Jun 2005 (UTC)

The word is definitely in current use (!) in the United States and is probably a portmanteau of "Amps capacity". The word "ampacity" gets 36,400 Google hits while the equivalent phrase "current carrying capacity" gets 32,400. I'm fairly certain "ampacity" is the term used in the National Electrical Code (US).

Now, as to how to make the article more accessible, I see that we have the word linked to "Ampere"; perhaps "Current (electricity)" might be another alternative. We could replace the word entirely, but it is a table heading so space is somewhat important. Or maybe we should just break down and write an Ampacity article. I guess I'm open to suggestions.

Atlant 16:09, 22 Jun 2005 (UTC)

The other headings have a description that does not use a unit word, followed by the unit. For example 'Area' and then 'mm²'. This heading has a description that embeds a particular unit, and then does not have the unit. If we added the unit, then it would certainly be a clue, particularly for those of us not familiar with the NEC terminology (perhaps lack of awareness is the reason they are searching Wikipedia).

So my first suggestion is to provide the unit, just like we do with 'mm²'. In this case, it would be the symbol for ampere 'A'. When I read documents in other languages, I can often decipher what they are talking about if they use the correct symbols (even in non-latin scripts such as japanese and arabic).

My second suggestion is to replace ampacity with some term like 'max current', 'current' or 'current capacity'. I am not fixed on the term, but I think the word 'current' should be in there.

My third suggestion relates to spacing. It is only now that I see that 'NEC' belongs to that heading. Copperwire, NEC and ampacity are not familiar terms to me, they are close to each other so I did not understand which was in which column. The same problem applies to units, the values in the 'Area' column overlap into the next one so reducing my confidence in what goes where throughout the table. The heading is a bit compact on my screen. It is on three lines and has two links in it. I am not a big fan of putting links on commonplace units, particularly when I am struggling to find the signal in the noise. I find that they add clutter, but I know other people have different opinions. Perhaps making the column wider would help so that no heading is more than two lines on respectable screen sizes.

Am I whining too much? I am just trying to put into text what I could point at in two minutes of speech. Bobblewik  (talk) 19:04, 22 Jun 2005 (UTC)

I have edited the table but feel free to put it back. It will need some further work anyway because it is half in one style and half another. We still need a term for the right hand column. It seems to me that the right hand column heading may contain too much information. The purpose of the table is, I presume, merely to translate between AWG values, mm values, resistance and current. The reference to 'NEC' and '60 degrees' and 'insulation' could all be taken out of the table because they are supporting information. What do you think? Bobblewik  (talk) 19:32, 22 Jun 2005 (UTC)

No, the extra conditions are absolutely required. Copper conductors can carry a lot of current before melting, but they'll start their insulation on fire a lot sooner than that. The standard insulation (so called "TW" wire) is rated up to 60C and those current ratings ("ampacities") are what will keep the conductor below 60C. So that column describes what the U.S. NEC stipulates for the maximum current allowed with 60C plastic insulation. We could write another column for 90C wire and a third for 105C (so-called "THHN") wire.

Atlant 23:53, 22 Jun 2005 (UTC)

You have reminded me of a conversation with an electrician about correct cabling and electrical devices in the home. He also mentioned the insulation melting as an issue. Your explanation is quite clear and helpful. Perhaps that is worthy of being in the article to explain why the current limits are set as they are. You also used the term 'current rating'. That seems quite a clear term to me. In order to make the table more self-explanatory, could we replace 'NEC ampacity' in the table heading with 'Current rating'? After all, confusion about that column heading is why I brought this topic up. Thanks. Bobblewik  (talk) 08:31, 23 Jun 2005 (UTC)

Please, use °C for degrees Celsius, always, and especially when, as in this article, you could well be referring to charge in coulombs whose symbol is C, or to the italic C often used for a variable representing some quantity related to this discussion and which isn't always italicized as it should be. You can write °C as °C in Wikipedia if you don't know how to get it on your keyboard or from the character list on the edit screen. And use a space between the unit and its symbol. Gene Nygaard 10:17, 23 Jun 2005 (UTC)

Bobblewik asks: Could we replace 'NEC ampacity' in the table heading with 'Current rating'?

I'd be in agreement with "Current rating with 60 °C insulation" (or whatever the proper Wikiform of "degrees celsius" is; I'm not sure I accept Gene Nygaard's request above as consistent with the accepted WIki style, although I can see a conflict between Celsius and Coulombs).

Now, can you fit all that in the table and still have it look pretty? :-)

(And remember, we really may want to add a 105 °C column as well! Heck, if we're going to make this great, we might as well make it GREAT!)

Atlant 11:50, 23 Jun 2005 (UTC)

I have done as you said. I am not sure what Gene means. I thought that we had put °C in the table. I a bit confused by all the various forms of little circles and hyphens or dashes. They all look the same to me.

I would also be interested in Gene's thoughts on the term 'ampacity'. I will leave it up to others to expand the body text a bit more. I think the bit in this talk page about insulation melting was helpful to me. Bobblewik  (talk) 11:58, 23 Jun 2005 (UTC)

205.200.98.7 adds that ampacity is also the term used by "the Canadian Electrical Code".

Atlant 17:04, 15 May 2007 (UTC)

It really is 10log10

The precise formula for American Wire Gauge of solid wire is

/* this is quite wrong...try it with no. 10 AWG, .1019 inches diameter, this formula then gives -10*log (pi *0.0081552)= 15.91 as the gauge number, plainly wrong. */

$AWG=-10*\log _{10}\left(\pi *Area\right)\,$

where the "Area" is the cross-sectional area of the wire in square inches (1 inch = 25.4 mm). Note that this uses the same "10log10" numbering system as is used with decibels. You may also use the following approzimations:

$\log(D)={\frac {36-AWG}{39}}*\log(92)-\log(200)$

---

$AWG=36-{\frac {39*\log(200D)}{\log(92)}}$

and log is a logarithm to any base.

I've cleaned up these comments. These formulas are wrong. I don't think we need many different formulas relating gauge number and diameter; anyone who's interested can do the math from what's given in the article, and festooning the equations with logarithms isn't, in my opinion, the best way to convey the idea. Forumulas are rare in practice, people interested in wire properties tend to use tables, in my experience.--Wtshymanski 02:17, 22 Jun 2005 (UTC)

The Wikipedia article suggests that there is something special about the numbers 36, 39, 92, and 200 and the AWG. O RLY?

PLEASE read the article cited as a reference by this Wikipedia article: Brooks, Douglas. "How to Gauge Traces" (PDF). Printed Circuit Design (Jan 2001).. The author (Douglas Brooks) admits that he obtained these (unusual) numbers by a best-fit line. More importantly, however, he revised the article in 7/2001 with the following note:

"My thanks to Brian Poindexter, Senior Design Engineer, Garmin Corporation, Olathe, KS. for pointing out in the original text an error in the formulas on page 2. The formulas should be, as now shown: Gauge = -10.7 + 10*Log10 (1/a); Area = 10^[-(AWG+10.7)/10]. Whatever error found its way into this paper did NOT find its way into the wire gauge calculator, which has always used these correct formulas."

Note that Douglas calls these new formulas the "correct formulas." They also make intuitive sense, using base-10 logarithms like many other applications in science. Note that I would simplify Douglas' new equations as follows:

$AWG=-10.7-10\log _{10}\left(Area\right)$

$Area=10^{\frac {-10.7-AWG}{10}}$

where Area is the cross-sectional area in square inches, and AWG is the gauge.

71.86.221.204 18:39, 3 July 2007 (UTC)

Ampacity rule of thumb

A simple model for ampacity is that the allowable heat flow out of the wire is proportional to its diameter. This heat is proportional to the square of the allowable current (ampacity) and inversely proportional to the square of the diameter; so the ampacity is proportional to the 1.5 power of the diameter. If the diameter doubles (approximately) every 6 wire sizes, the ampacity then doubles every 4 wire sizes. This is consistent with the NEC stipulation of 30, 20, and 15 amperes for 10, 12, and 14 AWG, respectively, and useful for roughly extrapolating ampacities for nearby AWG numbers. —Preceding unsigned comment added by 63.86.92.198 (talk) 21:16, 8 October 2008 (UTC)

Other methods of specification

I am fairly certain that Gerry Sussman once told a lecture audience that the wire gauge system was specified not as specific diameters of wire, but rather as wire with a certain resistivity (in ohms per thousand feet or similarly odd units). Is there any evidence that this is or was the case? 121a0012 21:28, 24 June 2007 (UTC)

I don't know. Perhaps you should ask Gerry. -- Mikeblas (talk) 02:21, 21 January 2008 (UTC)

Sounds bogus. From what I've read the first conductors used for a trans-Atlantic cable varied in resistivity by a factor of 2 or more from place to place along their lengths - but they were all the same diameter. --Wtshymanski (talk) 00:24, 25 September 2008 (UTC)

Certainly the International system defines wire size as "nominal" based upon its resistivity. I would certainly hope that this has been adopted for the American system as it is the key value for conductors. —Preceding unsigned comment added by 62.94.33.30 (talk) 15:41, 27 November 2008 (UTC)

Focus

The article is rambling quite a lot. Current carrying capacity, table of metric (forsooth!) standard wire sizes, discussion of I2R losses, etc. are all extraneous to the topic, which is adquately explained by a table. Has anyone proofed the current versions of these formulas, the last time someone put formulas in they were quite wrong. I don't know where the IEC sizes belong but it's surely not in an article called "American wire gauge". Perhaps in "wire" or elsewhere? --Wtshymanski 04:45, 18 July 2005 (UTC)

Considering that the AWG is a pretty odd measure in a world that is very much dominated by mm² wire specifications, I don't think it is helpful to remove the metric versions of the conversion formulas. After all, this is meant to be an encyclopedia for a global audience. People who look up AWG very often do so, because they have to convert an AWG spec into an IEC spec, or vice versa. I have carefully checked the formulas against several sources, including tables from the US NEC. I agree that there is a lot of rambling about current carrying capacity, and that this subject is far more complicated than what can be (and is) handled in this article. If you want to strengthen the focus, please start at that part of the article, rather than the metric variants of the conversion formulas. Markus Kuhn 09:55, 18 July 2005 (UTC)

Odd measure? I'm sure a significant part of the world's annual wire sales is specified in AWG. The table gives the square mm areas. People who work in the industry rarely use the formulas anyway, so two versions seems to be overkill. I'll try to find more relevant homes for the text in the article - we do have articles on electrical wiring that may be a better fit. --Wtshymanski 13:49, 18 July 2005 (UTC)

"Odd measure" was meant in the sense of "difficult to understand unless you know the definition or have a reference table". Markus Kuhn 14:26, 18 July 2005 (UTC)

The problem with the current-carrying capacity is that this is not simply a physical property of the cable. It is also an engineering judgement that involves ventilation and generous safety margins. For example, the current carrying capacities listed in the US NEC are a bit more conservative/generous than those used in Europe, possibly because in the US (where wood-frame buildings dominate) there is more worry about fires created by electrical accidents than in Europe (where brick-and-mortar buildings dominate). It is mostly because of such complexities that I suggest to move the current-capacity information into a separate article and start discussing it there properly. An interesting discussion of regional differences in current ratings is in one of the NEMA references at the end of the Electrical wiring article. I guess, Electrical wiring would be a good starting point from where such information should be easy to find. Markus Kuhn 14:26, 18 July 2005 (UTC)

Well, this is the article about the AMERICAN Wire Gauge, so it's entirely reasonable to state ampacities in terms of what the AMERICAN regulatory authority specifies. Really, the column is completely well specified: Copper wire, 60°C plastic insulation, and the NEC. Run more amps through that and your installation is not conformant to the regulations.

Atlant 15:47, 18 July 2005 (UTC)

I'll find a better home for the following :

Current-carrying capacity of wires

The ability of a wire to carry electric current (its ampacity) is limited by two factors:

• The amount of voltage lost to electrical resistance in the form of V = IR voltage drop and
• The amount of heating of the wire caused by the P = I2R power dissipated in the wire as a result of that voltage drop.

Both factors are affected by the cross-sectional area of the wire and that cross-sectional area is denoted in America by its AWG (gauge) number.

While copper (or aluminium) can carry substantial current before melting, practical plastic wire insulation will melt (allowing short circuits) or even catch fire at much lower temperatures, limiting the current-carrying capacity of any insulated wire to a much lower value than that point at which the wire itself will melt.

For relatively high-voltage circuits, the temperature of the insulation thus provides a limit to the current-carrying capacity of the wire and the wire gauge to be used must be selected to provide reliable, safe operation of the insulation. (And various kinds of insulation can withstand varying degrees of heat.) For low voltage circuits, it is instead the voltage drop as a result of IR losses that usually dominates the choice of wire gauge.

and

Outside Canada and the U.S., wire is typically specified in terms of its area in mm². The international standard manufacturing sizes for conductors in electrical cables are defined in IEC 60228.

--Wtshymanski 01:39, 21 July 2005 (UTC)

This article could suffice as a single paragraph of description and a table of conversion including the most common wire guages and the most common mm2 cross-sections and their equivalents in the other system —Preceding unsigned comment added by 62.94.33.30 (talk) 15:43, 27 November 2008 (UTC)

Cross section is wrong units!

The numbers in the kcmil column are clearly kmil^2. Either change the column heading, or fix the conversions.—Preceding unsigned comment added by 207.38.203.191 (talk • contribs)

Waht makes you say that? It seems right to me. You were probably making the same mistake I made at first, that you need to square the diameter in mil to get cmil, not proportional to diameter. SpinningSpark 07:23, 24 September 2009 (UTC)

Conversion table data

I think the conversion table should also include cross sections in mm², as this is the common way to classify wires outside of the USA.

You know what to do: Be bold! If you have or can generate the data, then please add it!

Atlant 13:16, 11 Apr 2005 (UTC)

-- this has already been done -- REW nov 3 2009. —Preceding unsigned comment added by 95.36.47.159 (talk) 08:42, 3 November 2009 (UTC)

Math notes

IMHO, formulas should aid in calculating things. People (like me!) looking for this article are interested in the diameter given an AWG number. So I added the formula with the natural exponent (e-to-the-power) and as little as possible additions and multiplications. Now calculating the diameter from an AWG number requires two constants, a multiplication, addition and exponentiation, compared to about twice as many operations on the calculator before. -- REW 3 nov 2009. —Preceding unsigned comment added by 95.36.47.159 (talk) 08:53, 3 November 2009 (UTC)

Note that the conversion from diameter D to AWG gauges could be written as

• AWG = 36 - 39 log₉₂(200D)

but that would probably confuse more people than it would help.

This is most useful in illustrating that for D = 0.005 inch

• AWG = 36 - 39 log₉₂(200·0.005) = 36 - 39 log₉₂(1) = 36 - 39·0 =36

and for D = 0.460 inch

• AWG = 36 - 39 log₉₂(200·0.46) = 36 - 39 log₉₂(92) = 36 - 39·1 = −3

where, for AWG gauges, −3 is written as 0000 or 4/0.

The formulas could also be simplified by defining a constant k equal to the 39th root of 92 (about 1.122932), but once again that would probably confuse more people than it would help. This is the constant ratio in the AWG classification; for example, the diameter of AWG20 is 1.122932 times the diameter of AWG21. Using this k, the formulas become

• D = 0.005 k^36-AWG
• AWG = 36 - log (200D)/log k, or
• AWG = 36 - log₁₀ (200D)/0.05035353

with the intermediate explanatory step

• log D = (36 - AWG) log k - log (200)
  

Gene Nygaard 17:32, 11 Feb 2005 (UTC)

This sounds almost as much fun as explaining why the aspirin pills used for aspirin therapy are 81 mg! "Where'd 81 come from?"

In any case, do we really need all these complex formulas? It sounds like you're leading to an explanation that would read something like the following:

Each size of wire in the American Wire Gauge is related to its neighboring wire sizes by the ratio 1.122932. (See footnote for the derivation of this value). For example, 0 (zero) gauge wire has a diameter of 0.3249 inches and the next smaller wire (1 gauge) has a diamter of 0.3249 / 1.122932 ~= 0.2893 inches.

We could then cast the formulas to simply say diameter = 0.3249 / (1.12932^gauge_number).

(Sorry, I don't know Tex or I'd try to make this example clearer, but you probably get my drift.)

And then in some tangled footnote we could bury the explanation of where we get the constant that approximates 1.122932.

Atlant 19:04, 11 Feb 2005 (UTC)

Did you notice that the formulas work for the diameter and areas in matric values, bit not in mils? This is because the AWG tables do not use the actual area for the value in the circ-mils column. The value in this column is the square of the diameter in mils. For example, for #1 wire, with 289 mils diameter, the area in circ-mils is listed as 83,700. This is close to the value of 83,521 one gets when squaring 289.Bvsmith1953 (talk)

Why?

Why 36? Why these sizes? Is there any logic behind the numbers they picked, or it was just random choice? --grin ✎ 07:21, 30 November 2009 (UTC)

AWG or SWG

There is an old British standaed called "Standard Wire Gauge". Is this the same as AWG ?? 80.229.222.48 20:33, 31 March 2007 (UTC)

<years later> No, that's why it has a different name. --Wtshymanski (talk) 14:31, 13 January 2011 (UTC)

Unused gauges of wire

Why is 11,13,15, etc listed as wire gauges? I'm pretty sure you can't buy those sizes, and even if you could, they would be so rare, why even bother to list them?

Magnetic wire (enamel coated wire for inductors and transformers) is available in both even and odd gauges. Hookup wire is normally available only in the even gauges as you note.

I used to prefer some 11 gauge speaker wire that I thought was really nice. It was quite impressive, to say the least, especially since it was a 2-conductor flat cable. So odd sizes are made... Additionally, if you were to combine any two wires, you can use the rule of thumb and the table to see what the resulting wire properties are.

Example: take my 2-conductors of 11 AWG. By the rule of thumb, combining them would equate to a single 8 AWG wire, which tells me that the max current is 40 to 55 amps, per the NEC table. I now need to read my insulation and see if it has a temperature rating. I like to saw logs! (talk) 08:06, 13 January 2011 (UTC)

Off topic for this article, but the NEC (and CEC) prohibits parallel conductors below some large size (1/0 AWG in CEC rule 12-208) - you can't parallel #14s to wire a stove, for example. You will observe that the sum of two smaller conductors' ratings is higher than the rating of a larger conductor with the same area; one reason to parallel conductors. You make better use of metal if you increase the periphery; power conductors really should be flat strips for heat dissipation. --Wtshymanski (talk) 14:31, 13 January 2011 (UTC)

number in brackets

What does the number in brackets at the end of a few of the entries in the ampacity column mean? It's meaning doesn't seem to be explained anywhere in the article. Plugwash (talk) 03:02, 21 January 2011 (UTC)

I am guessing they are the ratings when the cable is not in free air (for instance channeled into a wall or in the loft insulation). I can't be sure though as I only have access to the equivalent British standards, not the US standard this table is taken from. SpinningSpark 19:00, 22 January 2011 (UTC)

SWG on AWG

Why is there a Standard Wire Guage image on the American Wire Gauge Page??? The are not the same thing, 5/0 SWG is Smaller than 4/0 AWG and 13AWG == 15 SWGLarek (talk) 15:02, 5 June 2011 (UTC)

Ooh, never noticed that before. It is definitely not AWG, after carefully checking the hole ratios, they are not following the "rule of thumb" by sixes. I will move it to the proper article. SpinningSpark 15:49, 5 June 2011 (UTC)

Bartable template

I don't like the bars. The visual area that a bar shows is not proportional to the actual area of the wire, and it seems willfully perverse to describe the area of *round* objects by a *rectangular* bar. The last dozen entries are just wisps anyway and do not give any idea that a NO. 30 is still much heavier than a NO. 38 even though the wisps on screen are the same. Let's use a figure with *round* shapes whose area is proportional to wire area, or better yet a photograph. --Wtshymanski (talk) 13:40, 9 August 2011 (UTC)

I think that the bar lengths are meant to be proportional to the wire area. Bartable works like a bargraph, it is not meant to look like the wire cross section. SpinningSpark 15:27, 11 August 2011 (UTC)

I think the bars are a poor and lazy substitute for a properly-drawn figure or a photograph. The lengths are not proportional to wire area, scaling off my LCD - they seem to be meant to be proportional to diameter; but the bars are so thick, the eye is comparing "bar areas" and coming up with the wrong assessement of the relative sizes of wires. It's just a way of automatically padding up an article without adding any usable content. --Wtshymanski (talk) 16:13, 11 August 2011 (UTC)

Approximate stranded metric equivalents

SGBailey recently added a column approximate stranded metric equivalents to the table. I find these somewhat odd and in need of explanation, for a number of reasons:

• Could you please add an explanation and reference for the n/d notation used (I assume it is number of stands / diameter of a single strand in mm, but the table should say so).
• Where is this particular notation used? Metric cables are normally labeled in mm² cross section, therefore there is no need to look up anything in the column you added.
• Where do the particular figures that you added come from? Is is a selection from a particular product standard? If so, please add a reference!
• Why are there < and > signs? This does not make sense to me.

Unless you can answer/fix the above, I would suggest to revert these additions as they look very arbitrary and not very useful in their present form. Thanks.

Markus Kuhn 13:37, 9 August 2005 (UTC)

I've added some commentary on the metric stranded equivalents. Should it be decided that this is not the place for this information, I'll make a separate page along the lines of "equivalent wire sizes". -- SGBailey 13:47, 10 August 2005 (UTC)

In your added explanation, you say that the d in n/d is the area. But the equivalences that you have chosen match the mm diameter column, not the mm² area column. This now looks definitely wrong. If the notation you use is really based on area, then there seems no point in providing an equivalence table. Everyone who knows how to multiply can see that a 5x1 mm² strand is (for low frequency purposes) equivalent to a 5 mm² wire, etc. I don't think, we need or want to have a full multiplication table here. You also haven't answered my other questions. Markus Kuhn 14:31, 10 August 2005 (UTC)

The n/d notation is common in the international cable industry and refers to n=No of strands and d=diameter of each strand. Confusingly, in some instances (particularly with small wire sizes) d is sometimes replaced with cross-sectional area. — Preceding unsigned comment added by 81.3.116.254 (talk) 08:22, 7 September 2011 (UTC)

Extend the table beyond 40awg

I am working with wire that I measure at .0025" and I came here to get further data on it only to find that the table ends at 40awg. Well, wire finer than that is in common use (I bet the relays in your microwave oven use it -where mine came from). Further web searching found this table [1] (just as an example) which goes to 60awg and this table [2] which is referenced. Could someone please extend the table beyond 40awg from a reliable source? 76.232.7.132 (talk) 01:10, 15 September 2011 (UTC)

Yes, you could. SpinningSpark 05:54, 15 September 2011 (UTC)

What does the ASTM standard say? --Wtshymanski (talk) 13:23, 15 September 2011 (UTC)

ASTM B258-02 "Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Used as Electrical Conductors" tabulates sizes down to 56 AWG (0.49 mils), but some language in the standard says you can extrapolate wire sizes upward and downward. It would be good to have a reference that anyone actually makes wires with AWG numbers beyond the range in the ASTM standard, however; just because you can theoretically define AWG #100 doesn't mean anyone can actually manufacture AWG #100 wire (which would be, oh, about 0.46/(1.1229322^104) = 2.66 millionths of an inch in diameter; a mile of this would weigh about one-tenth of one millionth of a pound).--Wtshymanski (talk) 13:58, 15 September 2011 (UTC)

This manufacturer offers wires down to 60 awg, but on their FAQ page it is stated that 56 awg is the finest commercially practical size for magnet windings. This product claims to use flexible wire braided from 60 awg strands. SpinningSpark 17:31, 15 September 2011 (UTC)

"multiplies the area and weight by approximately 10"

I'm new to wire gauges, but if the area goes up by a factor of 10, doesn't the weight go up by a factor of 10^(1/2) for a given length of wire?--Wikimedes (talk) 17:42, 29 April 2012 (UTC)

By this time you've probably realized "area" and "weight" is proportional to the square of diameter. --Wtshymanski (talk) 23:11, 29 April 2012 (UTC)

You're right. I don't know what I was thinking.--Wikimedes (talk) 01:42, 30 April 2012 (UTC)

No harm, no foul. Now, if I'd made this mistake it would have been good for a revert war and at least one 24 hour block. --Wtshymanski (talk) 03:49, 30 April 2012 (UTC)

OCPD advice in table

The phrase "but use a ##A OCPD" is used repeatedly in the Tables of AWG wire sizes. I don't think it belongs there at all—it widens the column with some not-immediately-relevant electrician's HOWTO in a table of numeric values—and OCPD is unexplained jargon, the best translation I can find being "circuit breaker or fuse".

I'm adding an {{explain}} template to the 2nd & 3rd occurrences of OCPD, but I really think this should come out, or be addressed in a less intrusive way, and the link to Fuse (which I'm keeping for the first mention, even tho the term is unexplained in that article) is a bit head-scratching to the novice.

Incidentally, since NEC states fuse sizes must be size limited to 80% of their current rating, these smaller OCPD recommendations may be redundant or overkill. I'll leave that to editors more expert in these matters than I. / edg ☺ ☭ 14:29, 15 May 2012 (UTC)

I've taken it out; selecting over current protection devices is not the mission on an article on wire sizes, that's what the electrical codes are for. We don't even explain *which* NEC table is being abstratcted here - are these for copper or aluminum wire, free air or in cable or direct buried or buried in conduit, etc. ? The table would be sufficiently illustrative if it just said "Here's what the US code rates a single conductor in free air and with 60 C insulation, for the rest, see the full text of the NEC". --Wtshymanski (talk) 14:55, 15 May 2012 (UTC)

Gauge_Chart.pdf trouble

The "See Also" section here on American_Wire_Gauge links to a PDF: "A chart comparing all known wire gauges (PDF)" http://upload.wikimedia.org/wikipedia/en/2/28/Gauge_Chart.pdf

But that PDF has discrepancies with the table on this page, and it has one definite obvious typo. I'll referring to the table in the entry American_Wire_Gauge as "the page", and the grid in the PDF as "the PDF":

 AWG20:  **** DISCREPANCY: ±0.023mm or ±1/1000th of an inch ****
   Page: AWG20 = 0.812mm   = 0.0320"
   PDF:  AWG20 = 0.78892mm = 0.03106"

 AWG39:  **** OBVIOUS TYPO  ****
 PDF:  AWG39 = 0.00353mm = 0.00353" (!!!)  
  obvious typo -- same figure for inches and millimeters
 (incidentally, the page says AWG39 = 0.0897mm = 0.00353")

 AWG33: an odd discrepancy: difference of 2 microns, and 6/100,000"?
 Page: AWG33 = 0.180mm   = 0.00708"
  PDF: AWG33 = 0.17831mm = 0.00702"

Then there's some apparent rounding differences, if you consider the difference to be artifacts of the different number of decimal places to which the page and the PDF give figures for:

 AWG40: a one-micron rounding(?) discrepancy
 Page: AWG40 = 0.00314mm = 0.0799"
  PDF: AWG40 = 0.00314mm = 0.07976" 
     the "" figure should round to 0.0798

 AWG17: a one-micron rounding(?) discrepancy
 Page: AWG17 = 0.04525mm = 1.14935"
 PDF:  AWG17 = 0.0453mm  = 1.150"
  But .14935" doesn't round to .150, it rounds to .149"

 AWG12: a 1/1000th of an inch rounding(?) discrepancy
 Page:       AWG12 = 2.053"
 PDF:        AWG12 = 2.05232"
   But 2.05232 doesn't round to 2.053, it rounds to 2.052

 AWG9:  a 1/1000th of an inch rounding(?) discrepancy
 Page says:   AWG9 = 2.906"
 PDF says:    AWG9 = 2.90652"
   2.90652" rounds to 2.907", not to 2.906".

Aside from the one obvious typo at AWG39, where I know not to use the datum from there, I don't know which to consider authoritative- the American_Wire_Gauge page, or the PDF... nor do I know what to do about this situation. I hereby volunteer other people to figure this out and act on it! —sburke@cpan.org (talk) 05:43, 6 June 2012 (UTC)

Cross-section does NOT determine current-carrying capacity and electrical resistance.

At least, that is what I learned in school. It is the surface that caries the current, so I believe the surface area is more relevant than cross-sectional area. Could someone who knows what they are talking about comment on this and correct it if needed? The relevant statement is made (incorrectly, I believe) in the 4th paragraph of the introduction (7-Jul-2013).

I also find the use of logarithms base 92 completely bizarre and off-putting. Why in the world does anyone think that adds to the article? It is, imho, not.216.96.77.114 (talk) 17:51, 8 July 2013 (UTC)

Would it add to either the article or your knowledge to know that the log₉₂ is rather simple to calculate on calculators that have been widely available since the 1970s at least, and that this calculation is the most straightforward method to calculate AWG numbers given an arbitrary diameter in inches? It's not too bizarre because it flows directly from the formula above it using a little trick of rearranging the equation to solve for a different unknown. And even if you were complaining about this in the 19th century, there were still tables of logarithms that would have made the equation useful.

As to current carrying on the surface of a wire... Your memory has somewhat faded and you skipped over some important assumptions that are specifically stated in the article. Namely, "The table below assumes DC, or AC frequencies equal to or less than 60 Hz, and does not take skin effect into account." Skin effect in the sizes mentioned is mitigated by stranding, but since the concept is not vital to a discussion of AWG, it is mentioned in passing. I have a feeling you never learned anything about skin effect except in passing, and that the electrical engineers around you have solved it for you and you've never had to go far from the ideal characteristics based on diameter. You are clearly wrong in that surface area is dominant over cross-sectional area. AC current flows based on the frequency and the thickness, so you could say that frequency is the most relevant, followed by type of material, area, thickness, stranding, temperature, and insulation (not to mention voltage, EMF fields, noise, radiation, plasma, ionization, and hysteresis). You are trying to take a single point of induced impedance (skin effect) and say for some reason that it is the most important part of determining how much current a wire can carry. I gave you a host of other things that could very well cause similar havoc, none of which is relevant to AWG.

Just so lightning doesn't strike twice, I want to reiterate that if a voltage across a wire fluctuates, like when a cloud or something discharges a few trillion electrons to ground in a flash of light, then yeah, current skips the center of your body (like the brain) and travels like on the skin off your nose. It's no bid deal. Those electrons just can't find the time to go find friends inside the wire, or your body; they just find skin. But if you had a high voltage DC welder, the current would go for the meat and potatoes, like the center of the wire. They have all the time in the world to get those inner electrons moving and keep them moving. I like to saw logs! (talk) 09:17, 12 July 2013 (UTC)

Dispute

There are no forty wire gauges if it counts down from 36 to 0. — Preceding unsigned comment added by Jangirke (talk • contribs) 00:01, 13 October 2013 (UTC)

It is not 40 gauges from 36 to 0, it is 40 gauges from 36 to 0000. That is 36 gauges in the 1 to 36 range plus gauges 0, 00, 000, and 0000. SpinningSpark 10:07, 13 October 2013 (UTC)

MegaOhms per meter?

The table displays Ohms/km or MegaOhms/m. This should be the other way around: Ohm/m (or MOhm/1000km which should just be removed) — Preceding unsigned comment added by 83.98.233.229 (talk) 02:43, 1 December 2013 (UTC)

It's mΩ/m, lowercase m, that is, milliohms per metre, not MΩ/m, megaohms per metre. SpinningSpark 09:15, 1 December 2013 (UTC)

Fusing current

I'm a little unhappy including a list of "fusing current" values here. It's highly material and geometry dependent; the fusing current of a bit of wire depends on many factors other than the wire's inherent diameter, and those fusing values should come with a whole article worth of explanations and limitations. --Wtshymanski (talk) 20:25, 12 January 2011 (UTC)

Well the editor has specified copper as the material. At one time, fuse boards really did consist of bits of copper wire and there was an accepted correspondence between diameter and fusing current. I see no fundamental objection to Wikipedia containing this information, even if the reality is more complicated, provided it is sourced, which it is. What I would say is that this is not really directly relevant to the AWG article; fuse (electrical) would be a more appropriate place. SpinningSpark 19:54, 18 January 2011 (UTC)

I'm not sure how useful (a.k.a. notable) the information is, but the entire table is talking about cylindrical copper wire, so I really think that complaint is a red herring. And the fusing current, especially for small time intervals, actually doesn't depend too much on the environment because there isn't time for much heat transfer. What I would like to see on the talk page, or a footnote, are the actual formulas used. 71.41.210.146 (talk) 01:14, 24 March 2011 (UTC)

I was using the fusing current equations referenced in [8] and [9] for a nonstandard wire size and discovered that the original author of the Fusing Current portion of the AWG table omitted the "+1" term from the Onderdonk fusing current equation. The correct equation is, for Tmelt=1084.62 for copper and Tambient=25C, Ifuse = AREAcircularmils * SQRT( LOG( (TmeltC-TambientC) / (234-TambientC) +1) /(Tseconds * 33) ). This caused a 5% systematic error, which is less than the rounding error in some instances, but I wanted to at least get the table to correspond with the referenced equations. I kept values to at least two significant figures, but didn't restrict larger numbers to the same precision. (This is my first Wikipedia edit (yaaay) so I hope I didn't muck up the table format!) Wikiguinne (talk) 22:33, 29 May 2014 (UTC)

Looks good to me. The preview button is your friend if you want to avoid messing up anything. SpinningSpark 23:55, 29 May 2014 (UTC)

Voltage drops

This article would be more helpful to the general reader if it contained some building wiring voltage drops for typical max circuit amps on typical AWGs for reference lengths, such as 15A on 14 AWG 100 ft solid, and 15A on 16 AWG 50 ft ext cord. Until then, a link to something like this would help... -71.174.178.251 (talk) 02:40, 10 June 2014 (UTC)

• www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=8.286&voltage=120&phase=ac&noofconductor=1&distance=100&distanceunit=feet&amperes=15&x=61&y=9

Nonferrous

This may be part of the std, but as a practical matter, isn't a lot of zipcord and other awg stuff made of iron containing metals ? thanks — Preceding unsigned comment added by 50.195.10.169 (talk) 16:43, 4 March 2014 (UTC)

As far as I know, zip-cord does not commonly contain iron. What applications are you thinking of? Perhaps you are confused with zip-line (which isn't normally sized by AWG). In any case AWG sizes are the same regardless of the cable material so that is not really relevant. SpinningSpark 18:32, 4 March 2014 (UTC)

There are currently some zip-cord style cables for loudspeaker applications with clear PVC insulation that apparently use aluminum conductors for the "white" or "-" side, but not iron. — Quicksilver^{T @} 21:39, 26 February 2015 (UTC)

English Cross-Sectional Areas are not correct (??)

As it currently stands, the cross-sectional areas (given in kc mil^2) do not jibe with the wire diameters; each should be simply calculated by π*(d/2)^2 of the diameter, and while this formula works for the metric units, the English units are approximately 78% of the correct values. I don't have time to thoroughly fix the errors at this moment, and I'd also want to check the resistance/ft given, but these should be corrected soon as they may be used for significant Joule heating calculations. — Preceding unsigned comment added by 98.207.203.217 (talk) 23:51, 6 June 2015 (UTC)

Nevermind: These are just in very strange units, as referenced by the footnote! — Preceding unsigned comment added by 98.207.203.217 (talk) 19:48, 14 June 2015 (UTC)

Tables of AWG wire sizes

What are "Preece" and "Onderdonk"? These are not English or technical terms that I know of. Rich S 10001 (talk) 16:30, 27 March 2016 (UTC)

Sir William Henry Preece, KCB, FRS. I trust you have heard about him, if you know something about the history of electricity, telegraphy and wireless.

Onderdonk is certainly a british family name. The reference here is to the equation proposed by an electrical engineer named I. M. Onderdonk circa 1920.

SV1XV (talk) 18:29, 27 March 2016 (UTC)

Formulae

The formula for exceptionally small wire sizes is fine, but how about adding the closed-form formula for the normal case under the formula section? 72.130.227.252 (talk) 20:03, 23 March 2016 (UTC)

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Aught

Do Americans really say 'aught'? - "3/0 (common for large sizes) Pronounced 3 aught" as in /ɔːt/ or 'owt'? It seems odd to a British English speaker as 'aught' means 'anything' - the polar opposite of 'zero'. In the UK we would say '3-oh' or, less often, '3-zero'. Stub Mandrel (talk) 18:30, 2 September 2017 (UTC)

Yes, for example, "000-grit sandpaper" would be pronounced as "triple-aught-grit sandpaper". But I've seen it spelled more often as "ought", though "aught" is less-ambiguous and therefore might be preferable. The British sense of "aught" means "anything at all", perhaps a very small amount. This meaning seems to have drifted to mean "almost nothing" or ""zero" in American usage. See Names for the number 0 in English for details, with references. Reify-tech (talk) 18:48, 2 September 2017 (UTC)

Ampacity

Seems thes figures are the wrong way round for temperatures !! — Preceding unsigned comment added by 217.194.34.115 (talk) 11:56, 14 November 2016 (UTC)

Ampacities for AWG >=20 looks suspicious. Amperage for 75°C shall be higher than for 60°C, not lower ... --77.240.102.126 (talk) 16:48, 8 November 2017 (UTC)

Suspecting the numbers were mistakenly swapped between columns, I tried to verify it with the source, and the closest I can find is table 11 on page 49-16, available on Google Books: https://books.google.se/books?id=R67HARlhisYC&pg=SA49-PA16#v=onepage&q&f=false. That table doesn't have temperatures in the heading, though, but rather "Wiring in Free Air" and "Wiring Confined". If the first corresponds to 75°C and the latter to 60°C, swapping the numbers indeed makes for a good match (exactly for AWG 22, 24, 26, and 30, and within 0.02A for AWG 28 and 32). So I believe swapping the number would probably be an improvement, but since the reference doesn't exactly say what the table says, I'm a little wary of doing the edit myself... — Preceding unsigned comment added by 85.228.206.197 (talk) 13:32, 16 January 2018 (UTC)

Further explanation of stranded to bundled diameter ratios in American Wire Gauge

Hello Wtshymanski, Thank you for your undo. The numbers that I gave in that line follow directly from the equations in the article. It's just a matter of punching in the numbers. Although I don't know of a specific source for these particular calculations, you can easily check the accuracy of these numbers by simply plugging into the equations in the article. Because diameter and area are exponential functions of AWG, differences in gauge translate directly into ratios of diameters or areas.

The reason for adding this paragraph to the article is because sometimes the gauge of an existing stranded wire needs to be measured, either because it has no label or to verify the marking. Since it's difficult to measure bundle diameter accurately, and measuring a single strand is much easier and can be done with a wire gauge go-no-go tool such as a Starrett 281 or Mitutoyo 950-202, the gauge of the bundle then needs to be figured. Knowing the diameter and count of the strands, simply subtracting from the strand gauge is quick and accurate. Here is a screenshot of a Mathcad worksheet showing the simple method of calculation:

Calculation of diameter and area in Mathcad

Is there a WP template dealing with the direct results of plugging numbers into existing equations? If so, I'm all ears.

Given this additional information, I hope you will reconsider your undo. Thanks again, and I look forward to hearing from you.

Best Regards, Yankeepapa13 --Yankeepapa13 (talk) 19:33, 16 May 2019 (UTC)

And a comment from Reify-tech who very kindly notified me of the undo:

Your edits seem to be eminently reasonable in intent, and I have not formed a strong opinion about them one way or another. Somebody other than me removed your edits from the Wikipedia article, but I felt that you should get an explanation of what happened (WP:DBN). Wikipedia has non-obvious rules regarding references for claims made in an article. Please read WP:RS and WP:NOR if you haven't done so already. If you feel that you can justify the edits, you are welcome to put them back in, but you must be prepared to defend them. The place to discuss this and any other edits to the article is Talk:American wire gauge.

Either way, best wishes for your other further editing! You clearly have technical skills and are acting in good faith (WP:AGF), and Wikipedia needs your contributions. Cheers! Reify-tech (talk) 20:58, 16 May 2019 (UTC)

The addition will be fine as long as a third-party source is included - that's the basis of the other editor's removal. A (very weak) argument could be made in terms of WP:NOTAHOWTO, but this is such benign material that seems silly. I'll add it back with a source. Anastrophe (talk) 18:22, 17 May 2019 (UTC)

Unfortunately, I'm having trouble finding this particular formula from a reliable source. There are numerous cable equivalent charts, and a number of sites that will do the calculations for you. Unfortunately this is not an area of even layman's knowledge for me, so I should let someone else do such research and find an appropriate reliable source! Anastrophe (talk) 18:32, 17 May 2019 (UTC)

Hello Anastrophe, The formula is within this very article, as indicated in the stranded wire section. There's no need to look afar, just look above, in the American wire gauge article itself. The formula for diameter and area as functions of AWG are given right there. They're right there. Please let me know if you have any trouble finding them, and I'd be glad to assist further. --Yankeepapa13 (talk) 19:18, 17 May 2019 (UTC)

As I said, I barely qualify as a layman regarding this stuff. I had only looked at the diff with your change. Anastrophe (talk) 20:14, 17 May 2019 (UTC)

Don't specified engineering parameters require specified tolerances?

As this topic falls under "engineering", it would appear to me to demand tolerances on all specified parameters, such as wire diameter. Otherwise, the quantities seem meaningless. For example, what prevents vendors from selling "18 AWG" copper wire that has a diameter closer to 19 AWG? If there are no mandated tolerances, could they just say that "it's within industry tolerances"? As the copper material (scaling with wire cross sectional area) dominates the cost of production, this would be a great way to increase profits! Of course, I tried to google such tolerances, but found nothing.

I became interested in this question when I measured some 18AWG solid (un-stranded) hook-up wire, and found a diameter of 1.00mm, instead of the nominal 1.024mm, almost a 5% deficit in cross sectional area. I wonder — might the most restrictive tolerance be specified on electrical resistance per unit length, rather than only diameter, allowing some degree of trade-off between diameter and material purity? Layzeeboi (talk) 23:24, 11 April 2019 (UTC)

I would argue that this is not an engineering "Specification" but rather an engineering "Standard". As such what is set out here is the nominal wire dimensions from which properties can be derived for various materials and tempers. It is for a Manufacturer to specify an appropriate tolerance associated with this nominal value, where it is quoted, as it will be specific to the manufacturing process and material composition employed. Paragraph 10 (Tolerances) of the ASTM B258-18 backs this up. --ChrisMatthewsUK (talk) 07:08, 4 May 2020 (UTC)

Reference to (ASTM B258)

Hello, this is my first go at contributing to Wikipedia so please excuse me if i don't crack the protocols straightaway or misspeak.

I notice that Reference 1 (ASTM B258-14) has been superseded by ASTM B258-18 . I am trying to obtain this standard through my employer and, if i succeed, I will provide some further detail as to the extent and nature of the changes. If no-one else offers to incorporate the necessary changes (should there be any) i will endeavour to conduct the edit but, again, this would be a first for me and I may make mistakes.

ChrisMatthewsUK (talk) 08:54, 30 April 2020 (UTC)

I wouldn't worry about it. The article is about "American Wire Gauge", not the ASTM standard B258. It's sufficient for the purposes of the article that B258 is cited as the governing standard, but chasing standards updates is a never-ending and low-value activity here. Unless there's some shocking new development in the 2018 edition, you can probably find much more critical problems on the Wikipedia that would benefit from your energy. Happy editing! --Wtshymanski (talk) 18:25, 30 April 2020 (UTC)

If only the auditors would agree with this approach! i might quote you when next they visit my lab and see how i fair? :) -- ChrisMatthewsUK (talk) 07:14, 4 May 2020 (UTC)

Usage and list

This page lacks info on the usage of each of the sizes of the wire gauges. It also lacks a size list. Firestar464 (talk) 03:02, 12 May 2020 (UTC)

But this isn't a textbook or how-to guide. Wire is used for a lot of things which would be trivial and boring to list exhaustively. --Wtshymanski (talk) 01:05, 14 May 2020 (UTC)

A Commons file used on this page or its Wikidata item has been nominated for deletion

The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion:

• AWG calculation in Mathcad software.png

Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 05:47, 25 April 2021 (UTC)

Fusing (electrical)

Proposal: To create a new article about wire fusing times and -currents, while keeping the tabular fusing data in American wire gauge. The new article can include:

• Equations that predict fusing current and/or time like those proposed by Preece and Onderdonk,
• lists of assumptions and limitations of the equations,
• a physical background and derivation of the equations,
• References to the corresponding theoretical and experimental research.

Article title proposal: "Fusing (electrical)"

This topic can also be added in Fuse (electrical), but that article is already pretty lengthy. What do you think?

Johan van Ravenhorst (talk) 07:48, 16 December 2021 (UTC)

A Commons file used on this page or its Wikidata item has been nominated for deletion

The following Wikimedia Commons file used on this page or its Wikidata item has been nominated for deletion:

• Gauge Chart.pdf

Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 21:36, 12 July 2022 (UTC)