The table below lists the wire Characteristics for different gauges of
the American Wire Gauge [AWG].
The American Wire Gauge provides a
means of specifying wire diameters.
For each different AWG [wire size]
the table provides the Diameter [in mils], the resistance per 1000 foot,
the current carrying capability [Ampacity], and Pounds per Foot [number
of feet required to weigh 1 pound].
The AWG is based upon a constant ratio of cross-section between wires of successive gage numbers.
Read the notes below the table to
determine how the Ampacity was derived. The larger the AWG number, the
smaller diameter wire. The table is based on an ambient temperature of
25oC. However the next link provides additional temperatures.
Some of the standard wire sizes used in a number of
Interface Buses [for data lines] are #22AWG, #24AWG, #26AWG, and 30AWG.
Refer here for a quick guide to Wire Gauge by Resistance Table.
A
listing of Electronic bus standards are located on the Buses page.
Another table near the bottom of the
page provides copper current carrying ability [Ampacity] for Teflon
insulated wire. Related; Cable Derating. Conductor size is based one or more of the following
considerations:
Current carrying capacity [inducing a rise in wire temperature, in
high-voltage lines], Short circuit current, or Voltage drop [long low
voltage lines].
AWG Copper Wire Table
AWG
Diam. (mils)
Circular mils
Ohms/1000ft
Current Carrying
Fusing Current
Feet per Pound
0000
460
212000
0.050
-
-
1.56
000
410
168000
0.063
-
-
1.96
00
365
133000
0.077
-
-
2.4826
0
324.85
105531
0.096
-
-
3.1305
1
289.3
83694
0.1264
119.6
-
3.947
2
257.6
66358
0.1593
94.8
-
4.977
3
229.4
52624
0.2009
75.2
-
6.276
4
204.3
41738
0.2533
59.6
-
7.914
5
181.9
33088
0.3915
47.3
-
9.980
6
162
26244
0.4028
37.5
668
12.58
7
144.3
20822
0.5080
29.7
561
15.87
8
128.5
16512
0.6405
23.6
472
20.01
9
114.4
13087
0.8077
18.7
396
25.23
10
101.9
10384
1.018
14.8
333
31.82
11
90.7
8226
1.284
11.8
280
40.12
12
80.8
6529
1.619
9.33
235
50.59
13
72.0
5184
2.042
7.40
197
63.80
14
64.1
4109
2.575
5.87
166
80.44
15
57.1
3260
3.247
4.65
140
101.4
16
50.8
2581
4.094
3.69
117
127.9
17
45.3
2052
5.163
2.93
98.4
161.3
18
40.3
1624
6.510
2.32
82.9
203.4
19
35.9
1289
8.210
1.84
69.7
256.5
20
32.0
1024
10.35
1.46
58.4
323.4
21
28.5
812
13.05
1.16
-
407.8
22
25.3
640
16.46
.918
41.2
514.12
23
22.6
511
20.76
.728
-
648.4
24
20.1
404
26.17
.577
29.2
817.7
25
17.9
320
33.0
.458
-
1031
26
15.9
253
41.62
.363
20.5
1300
27
14.2
202
52.48
.288
-
1639
28
12.6
159
66.17
.228
14.4
2067
29
11.3
128
83.44
.181
-
2607
30
10.0
100
105.2
.144
10.2
3287
31
8.9
79
132.7
.114
-
4145
32
8.0
64
167.3
.090
-
5227
33
7.1
50.125
211.0
.072
-
6591
34
6.3
39.75
266.0
.057
5.12
8310
35
5.6
31.5
335
.045
4.28
10480
36
5.0
25.0
423
.036
3.62
13210
37
4.45
19.83
533
.028
-
16660
38
3.97
15.7
673
.022
2.5
21010
39
3.5
12.47
848
.018
-
26500
40
3.14
9.89
1070
.014
1.77
33410
41
2.8
7.842
-
-
1.52
-
42
2.494
6.219
-
-
1.28
-
43
2.221
4.932
-
-
1.060
-
44
1.978
3.911
-
-
0.916
-
45
1.761
3.102
-
-
-
-
46
1.568
2.460
-
-
-
-
47
1.397
1.951
-
-
-
-
48
1.244
1.547
-
-
-
-
49
1.107
1.227
-
-
-
-
50
0.986
0.973
-
-
-
-
Table of Bare Copper Wire
General Notes:
The wire size is different between the American Wire Gage [AWG] and the British standard. The table above only lists the AWG standard.
AWG [American Wire Gauge] may also be called the Brown and Sharpe (B&S) Wire Gauge. [note]
The Birmingham Wire Gauge [BWG] is used for steel armor wire. [other wire gauge standards]
Watch for round-off errors, as many numbers were rounded. Use the table as a guide. [Equivalent Cross-Sections of Wire]
The weight [pound per foot] does not include wire insulation. The weight of the wire is critical in some applications. More data [AWG Table for 25C - 65C]
Circular mils is the diameter squared in mils. [Table of AWG sizes in metric]
The editor has never seen the American Wire Gauge [AWG]
Current Notes:
The current shown per wire size listed above is based on 1 amp/ 700 Circular mils, other tables provide different current per wire size, and
different current for open air ~ check your local electrical code for the
correct current capacity [Ampacity]. The 1 amp/ 700 Circular mils seems
to be the most conservative, other sites provide/allow for 1 amp per 200
or 300 Circular mil. For shot wire lengths use 1A/200 Circular mil, for
longer wire runs use 300 Circular mil, and for very long wire runs use
the table above, 1 amp / 700 Circular mil.
The current rating is listed based on permissible voltage drop and not
conductor heating.
The ability of a wire to carry a given amount of current is affected by a
number of additional factors, which are not accounted for in the AWG
table above. The ambient temperature of the surrounding air, wire
insulation, and number of other wires bundled together [provided
below].
Ampacity relates to the ability of the conductor to carry current [amps]
before the cable over heats. I understand there are hundreds of Ampacity
tables for many different conditions. The numbers above are but one
example. Ampacity Tables for many conditions:
IEEE Standard 835, IEEE Standard Power Cable Ampacity Tables
IEEE Standard 848, Procedure for the Determination of the Ampacity
Derating of Fire Protected Cables
ICEA P-54-440, NEMA Pub. No. WC 51 - Ampacities of Cables in Open-Top
Trays.
The National Electrical Code [NEC] requires their own cable sizing for
premises wiring. Refer to the NEC rules to determine building wiring, as
this page relates to electronic equipment wiring. For reference, the
ampacity of copper wire at 300C for common wire sizes
14 AWG may carry a maximum of 20 Amps in free air, or 15 Amps as part of
a 3 conductor cable.
12 AWG may carry a maximum of 25 Amps in free air, or 20 Amps as part of
a 3 conductor cable.
10 AWG may carry a maximum of 40 Amps in free air, or 30 Amps as part of
a 3 conductor cable.
8 AWG may carry a maximum of 70 Amps in free air, or 50 Amps as part of a
3 conductor cable.
The wire fusing [melting] current is based on the material the wire is
made of, the diameter of the wire and the melting point of the the
material. The wire fusing current of a wire is provided in tables as
constant current or as [a larger] current for some given amount of
time.
I found this formula used on a few different sites [un-verified];
I=Ad(3/2) @ d is in inches, A is a constant: A = 10,244 for
Copper. A = 7,585 for Aluminum.
I have listed a number of values for fusing current in the table above,
for selected AWG sizes.
Cable manufacturers will provide different numbers based on the
insulation used for the wire.
Use the table below to off-set the conservative current carrying numbers
in the table above, and the fusing current. The table below lists copper
wire with a Teflon [TFE] insulation. Teflon insulation has a higher
operation temperature range then other insulators, for example PVC. The
table below is based on data derived from MIL-STD-975, using
700C as the operating temperature. To derate based on number
of wires in a bundle:
IBW = ISW x (29 - #wire) / 28 @ [1 to 15
Bundled wires]
IBW = ISW x (0.5) @ [more then 15 Bundled
wires]
ISW = Single wire
IBW = Bundled wires
To derate by temperature use; derate by 80% at 150oC, 70% at
135oC, or 50% at 105oC (per MIL-STD-975)
I have seen one other Military Specification [MIL-STD-xx] for copper wire
current capability. That standard [I did not note the standard number]
listed AWG 18 [for example] as 10 amps with TFE insulation. That
indicates that this additional military specification uses the same data
listed in the table above, but may be listed for 250C, and not
700C as the table uses. So this table above has already been
derated for 700C.
This page provides a conservative guide for Ampacity for bare copper wire
[700 Circular mils/amp] , the melting [point] current for bare copper
wire, and the Ampacity for TFE coated copper wire. The American Wire Gage
[AWG] for bare copper wire is also listed. Refer to the National
Electrical Code [NEC] to determine cable sizing for premises wiring. This
page represents my notes on the subject, purchase one of the standards or
specifications referenced on this page when doing professional
work.
Also see the Wire Insulation Color Code page; Color
coding of wire insulation based on application.
Determine cable length vs. voltage drop. Determine cable length vs. Heat
increase.
