Hi
Wire Gauge) Numbers
Some types of wire
Note: For an understanding of the AWG numbers, you may want to first see the
section: "
American Wire Gauge (AWG) table for annealed copper wire".
A semi-infinite variety of wire and cable is used in modern appliances,
electronics, and construction. Here is a quick summary of the buzz words
so you will have some idea of what your 12 year old is talking about!
* Solid wire: The current carrying conductor is a single solid piece of
metal
(usually copper. It may be bare, tinned (solder coated), silver plated, or
something else.
Solid wire may be used for general hookup inside appliances and electronics,
and building (and higher power wiring) but not for cords that need to be
flexible and flexed repeatedly.
* Stranded wire: The current carrying conductor consists of multiple strands
of copper or tinned copper (though other metals may be found in some cases).
The individual strands are NOT insulated from one-another. The wire gauge
is determined by the total cross sectional area (which may be a bit greater
than the specified AWG number due to discrete number of strands). See the
section: "
What about stranded wire?".
Stranded wire is used for general hookup, building wiring, etc. It is
easier to position than solid wire (but tends not to stay put) and more
robust when flexed repeatedly. Cordsets always use finely stranded wire
but despite this, may develop problems due to flexing after long use.
* Magnet wire: This is a solid copper (or sometimes aluminum or silver)
conductor insulated with a very thin layer of varnish or high-tech plastic.
This coating must be removed either chemically, by heating in a flame, or
fine sandpaper, before the wire can be connected to anything.
Magnet wire is used where a large number of turns of wire must be packed as
tightly as possible in a limited space - transformers, motors, relays,
solenoids, etc.
The very thin insulation is susceptible to nicks and other damage.
* Litz wire: This is similar to stranded wire EXCEPT that the strands are
individually insulated from each other (like multiple pieces of magnet
wire).
Litz wire is used in high frequency transformers to reduce losses (including
the skin effect which results in current only traveling near the surface
of the wire - using multiple insulated strands increases its effective
surface area).
Like magnet wire, the insulation needs to be removed from all strands before
making connections.
* Tinsel wire: A very thin, metallic conductor is wound around a flexible
cloth or plastic core.
Tinsel wire is found in telephone and headphone cords since it can be made
extremely flexible.
Repair is difficult (but not impossible) since it very fine and the
conductor must be unraveled from the core for soldering. The area of the
repair must be carefully insulated and will be less robust than the rest of
the cord.
* Shielded wire: An insulated central conductor is surrounded by a metal
braid
and/or foil shield.
Shielded wire is used for low level audio and video, and other analog or
digital signals where external interference needs to be minimized.
* Coaxial cable: This is similar to shielded wire but may be more robust and
have a specified impedance for transmitting signals over long distances.
* Zip cord: This is 2 or 3 (or sometimes more) conductor cable where the
plastic insulation is scored so that the individual wires can be easily
separated for attachment to the plug or socket.
* 14/2, 12/3, etc.: These are the abbreviations used for building
(electrical)
wire like Romex (which is one name brand) and for round or zip-type cordset
wire. The conductor material is usually copper.
Note: Some houses during the '50s and '60s were constructed with aluminum
wiring which has since been found to result in significantly increased risk
of fire and other problems. For more information, see the references listed
in the section: "
Safe electrical wiring".
However, aluminum wiring is safe
if installed according to very specific guidelines (and is used extensively
in power transmission and distribution - probably for your main connection
to the utility - due to its light weight and low cost).
The first number is the AWG wire gauge.
The second number is the number of insulated conductors (excluding any bare
safety ground if present). For example:
- A 14/2 Romex cable has white and black insulated solid #14 AWG current
carrying conductors and a bare safety ground (some older similar types of
cable had no safety ground, however).
- A 16/3 cordset has white, black and green insulated stranded #16 AWG wires
(or, overseas, blue, brown, and green or green with yellow stripe).
17.2) So, where did AWG come from?
Nearly everyone who has done any sort of wiring probably knows that the AWG
or
American Wire Gauge number refers to the size of the wire somehow. But how?
(From: Frank ([EMAIL PROTECTED])).
According to the 'Standard Handbook for Electrical Engineers' (Fink and
Beaty)
the 'gauge' you referenced to is 'American Wire Gauge' or AWG and also known
as Brown & Sharp gauge.
According to above handbook, the AWG designation corresponds to the number
of
steps by which the wire is drawn. Say the 18 AWG is smaller than 10 AWG and
is
therefore drawn more times than the 10 AWG to obtain the smaller cross
sectional area. The AWG numbers were not chosen arbitrary but follows a
mathematical formulation devised by J. R. Brown in 1857!
17.3) For the marginally mathematically inclined
Each increase of 3 in the gauge halves the cross sectional area. Each
reduction by 3 doubles it. So, 2 AWG 14 wires is like one AWG 11.
It seems that everyone has their own pet formula for this (though I prefer
to just check the chart, below!).
(From: Tom Bruhns ([EMAIL PROTECTED])).
As I understand it, AWG is defined to be a geometric progression with AWG
0000
defined to be 460 mils diameter and 36 gauge defined to be 5.000 mils
diameter.
This leads directly to the formula:
Diameter(mils) = 5 * 92^((36-AWG)/39)
That is, 460 mils is 92 times 5 mils, and the exponent accounts for 39 steps
of AWG number starting at 36 gauge.
(From: David Knaack ([EMAIL PROTECTED])).
You can get a fairly accurate wire diameter by using the equation:
Diameter(inches) = 0.3252 * e^(-0.116 * AWG)
where 'e' is the base of the natural logarithms, 2.728182....
I don't know where it came from, but it is handy (more so if you can do
natural
base exponentials in your head).
In its simplest form, the cross sectional area is:
A(circular mils) = 2^((50 - AWG) / 3)
17.4) American Wire Gauge (AWG) table for annealed copper wire
(Similar tables exist for other types of wire, e.g., aluminum.)
(Table provided by: Peter Boniewicz ([EMAIL PROTECTED])).
Wire Table for AWG 0000 to 40, with diam in mils, circular mils,
square microinches, ohms per foot, ft per lb, etc.
AWG Dia in Circ. Square Ohm per lbs per Feet/ Feet/ Ohms/
gauge mils Mils MicroIn 1000 ft 1000 ft Pound Ohm Pound
-------------------------------------------------------------------------
0000 460.0 211600 166200 0.04901 640.5 1.561 20400 0.00007652
000 409.6 167800 131800 0.06180 507.9 1.968 16180 0.0001217
00 364.8 133100 104500 0.07793 402.8 2.482 12830 0.0001935
0 324.9 105500 82890 0.09827 319.5 3.130 10180 0.0003076
1 289.3 83690 65730 0.1239 253.3 3.947 8070 0.0004891
2 257.6 66370 52130 0.1563 200.9 4.977 6400 0.0007778
3 229.4 52640 41340 0.1970 159.3 6.276 5075 0.001237
4 204.3 41740 32780 0.2485 126.4 7.914 4025 0.001966
5 181.9 33100 26000 0.3133 100.2 9.980 3192 0.003127
6 162.0 26250 20620 0.3951 79.46 12.58 2531 0.004972
7 144.3 20820 16350 0.4982 63.02 15.87 2007 0.007905
8 128.5 16510 12970 0.6282 49.98 20.01 1592 0.01257
9 114.4 13090 10280 0.7921 39.63 25.23 1262 0.01999
10 101.9 10380 8155 0.9989 31.43 31.82 1001 0.03178
11 90.74 8234 6467 1.260 24.92 40.12 794 0.05053
12 80.81 6530 5129 1.588 19.77 50.59 629.6 0.08035
13 71.96 5178 4067 2.003 15.68 63.80 499.3 0.1278
14 64.08 4107 3225 2.525 12.43 80.44 396.0 0.2032
15 57.07 3257 2558 3.184 9.858 101.4 314.0 0.3230
16 50.82 2583 2028 4.016 7.818 127.9 249.0 0.5136
17 45.26 2048 1609 5.064 6.200 161.3 197.5 0.8167
18 40.30 1624 1276 6.385 4.917 203.4 156.6 1.299
19 35.89 1288 1012 8.051 3.899 256.5 124.2 2.065
20 31.96 1022 802.3 10.15 3.092 323.4 98.50 3.283
21 28.46 810.1 636.3 12.80 2.452 407.8 78.11 5.221
22 25.35 642.4 504.6 16.14 1.945 514.2 61.95 8.301
23 22.57 509.5 400.2 20.36 1.542 648.4 49.13 13.20
24 20.10 404.0 317.3 25.67 1.223 817.7 38.96 20.99
25 17.90 320.4 251.7 32.37 0.9699 1031.0 30.90 33.37
26 15.94 254.1 199.6 40.81 0.7692 1300 24.50 53.06
27 14.20 201.5 158.3 51.47 0.6100 1639 19.43 84.37
28 12.64 159.8 125.5 64.90 0.4837 2067 15.41 134.2
29 11.26 126.7 99.53 81.83 0.3836 2607 12.22 213.3
30 10.03 100.5 78.94 103.2 0.3042 3287 9.691 339.2
31 8.928 79.70 62.60 130.1 0.2413 4145 7.685 539.3
32 7.950 63.21 49.64 164.1 0.1913 5227 6.095 857.6
33 7.080 50.13 39.37 206.9 0.1517 6591 4.833 1364
34 6.305 39.75 31.22 260.9 0.1203 8310 3.833 2168
35 5.615 31.52 24.76 329.0 0.09542 10480 3.040 3448
36 5.000 25.00 19.64 414.8 0.07568 13210 2.411 5482
37 4.453 19.83 15.57 523.1 0.06001 16660 1.912 8717
38 3.965 15.72 12.35 659.6 0.04759 21010 1.516 13860
39 3.531 12.47 9.793 831.8 0.03774 26500 1.202 22040
40 3.145 9.888 7.766 1049.0 0.02993 33410 0.9534 35040
41 2.808 7.860 6.175 1319 0.02379 42020 0.758 55440
42 2.500 6.235 4.896 1663 0.01887 53000 0.601 88160
43 2.226 4.944 3.883 2098 0.01497 66820 0.476 140160
44 1.982 3.903 3.087 2638 0.01189 84040 0.379 221760
45 1.766 3.117 2.448 3326 0.00943 106000 0.300 352640
46 1.572 2.472 1.841 4196 0.00748 133640 0.238 560640
Ohms per 1000 ft, ft per Ohm, Ohms per lb, all taken at 20 degC (68 degF).
Note: Values for AWG #41 to #46 extrapolated from AWG #35 to #40 based on
wire
gauge formula.
17.5) What about stranded wire?
(From: Calvin Henry-Cotnam ([EMAIL PROTECTED])).
In addition to the cross-section area, there are a few other factors. First
off, a stranded wire effectively has more surface area than a solid wire of
the same gauge, but much of this surface is "inside" the wire.
I checked out the label of a spool of #18 stranded wire and found it was
comprised of 16 strands of #30 wire. Given the info above that each
reduction
of 3 in the gauge, then #18 has a cross-section area that is 16 times
greater
than #30 -- so it *appears* to translate exactly.
Looking through a catalog for wire, I found that this more-or-less holds
true,
though the occasional wire might have an extra strand or two. Here is what
I
quickly found -- there are many more, but this is a sample:
17.6) Overall gauge Typical stranded wires made up of
#32 7 x #40
#30 7 x #38
#28 7 x #36
#26 7 x #34
#24 7 x #32 19 x #36
#22 7 x #30 19 x #34
#20 7 x #28 10 x #30 19 x #32
#18 16 x #30
#16 19 x #29 26 x #30
#14 41 x #30
#12 65 x #30
#10 65 x #28
#8 84 x #27
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