AWG Copper Wire Table
AWGDiam. (mils)Circular milsOhms/1000ftCurrent CarryingFusing
CurrentFeet per Pound
00004602120000.050--1.56
0004101680000.063--1.96
003651330000.077--2.4826
0324.851055310.096--3.1305
1289.3836940.1264119.6-3.947
2257.6663580.159394.8-4.977
3229.4526240.200975.2-6.276
4204.3417380.253359.6-7.914
5181.9330880.391547.3-9.980
6162262440.402837.566812.58
7144.3208220.508029.756115.87
8128.5165120.640523.647220.01
9114.4130870.807718.739625.23
10101.9103841.01814.833331.82
1190.782261.28411.828040.12
1280.865291.6199.3323550.59
1372.051842.0427.4019763.80
1464.141092.5755.8716680.44
1557.132603.2474.65140101.4
1650.825814.0943.69117127.9
1745.320525.1632.9398.4161.3
1840.316246.5102.3282.9203.4
1935.912898.2101.8469.7256.5
2032.0102410.351.4658.4323.4
2128.581213.051.16-407.8
2225.364016.46.91841.2514.12
2322.651120.76.728-648.4
2420.140426.17.57729.2817.7
2517.932033.0.458-1031
2615.925341.62.36320.51300
2714.220252.48.288-1639
2812.615966.17.22814.42067
2911.312883.44.181-2607
3010.0100105.2.14410.23287
318.979132.7.114-4145
328.064167.3.090-5227
337.150.125211.0.072-6591
346.339.75266.0.0575.128310
355.631.5335.0454.2810480
365.025.0423.0363.6213210
374.4519.83533.028-16660
383.9715.7673.0222.521010
393.512.47848.018-26500
403.149.891070.0141.7733410
412.87.842--1.52-
422.4946.219--1.28-
432.2214.932--1.060-
441.9783.911--0.916-
451.7613.102----
461.5682.460----
471.3971.951----
481.2441.547----
491.1071.227----
500.9860.973----
Table of Bare Copper WireGeneral 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.The Birmingham Wire Gauge [BWG] is used for steel armor
wire.Watch for round-off errors, as many numbers were rounded. Use
the table as a guide.The weight [pound per foot] does not include
wire insulation. The weight of the wire is critical in some
applications.Circular mils is the diameter squared in mils.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. 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 TablesIEEE
Standard 848, Procedure for the Determination of the Ampacity
Derating of Fire Protected CablesICEA 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 sizes14 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.This formula is 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.
Aluminum wire properties are listed under on theAluminum
electrical WirepageManufacturers listing forelectrical Wire and
Cable{This Web Site}
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= ISWx (29 - #wire) / 28 @ [1 to 15 Bundled wires]IBW=
ISWx (0.5) @ [more then 15 Bundled wires]ISW= Single wireIBW=
Bundled wiresTo derate by temperature use; derate by 80% at 1500C,
70% at 1350C, or 50% at 1050C (per MIL-STD-975)Copper Wire TFE
Insulated
AWGCurrent CarryingAWGCurrent Carrying
001690147
2108481
660844
10331225
14191613
189.2206.5
224.5243.3
262.5281.8
301.3--
DC Wire Table
Wire Loss Tables for Solar Electric SystemsIncludes 12, 24, and
120 volt charts and aMetric to AWG size conversion table.This isa
five percenttable which means at these amperage ratings at the
listed distances, 5% of the power would be lost to resistance. Five
percent is normally acceptable in low voltage systems, butif you
want a 2% figure, divide the given distances by 2.5. For a 10% loss
multiply the distance by 2. For distances at 48 volts, double the
24 volt distances for a 5 percent loss figure. For 240 volt 5%
loss, double the 120 volt distances. These distances include the
NEC requirement for current over sizing of 25%.Example: For a pump
drawing 9 amperes at 24 volts, located 88 feet from the battery
bank: look at the center table for 24 volts. In the far left column
find the next number higher than 9 (which is 10) and follow that
line across the table until you find a distance figure greater than
88. At the top of the column find the gauge of wire (#8) that
should be used. This method insures that wire losses are kept to an
acceptable level without spending too much money on extra-heavy
cable. Using a heavier wire than indicated, however, will result in
even higher efficiencies and we do sometimes invest in the next
larger gauge. Wire can get expensive, and it may not be worth the
money to get that last 1% if you have to go to a much larger wire
size.
Some of the newer grid tie systems inverters, such as the Sunny
Boy, use up to 600 volts DC. Generally in these systems loss in
wire is nothing to worry about. HOWEVER - you will have to be more
careful about selecting and installing the wiring - high voltage DC
is not something you want to do a 2nd rate wiring job on. Make sure
the insulation is rated for 600 volts, and that there is no damage
to the wire or insulation.We have also included a wire chart for
convertingMetric to AWG(American Wire gauge) sizes.All distances
are in FEETDo not use any wire sizes that might fall into the red
zone - this would exceed the amperage rating of the wire and it may
overheat and burn.
120 Volt AC or DC chartAmpsin WireWattsat
120V#14#12#10#8#6#4#21/02/03/0
2240422656
4480187328516
6720141225328562
8960103159272422666
10120084131216337534
1518005684131225356562
202400651031-8272422675
25300084131216337543
30360065.63112178281450722
40480084131216337543675
50600067103171272431543684
24 Volt DC chartAmpsin WireWattsat
24V#14#12#10#8#6#4#21/02/03/0
124169262412675
24884131207337532
4963766103169267
6144284566112178282
819221325484133216
1024017264367107169270
153601117264571112180289
204801321375484135217270343
2560017264367108172217274
307201322365690144180228
4096017264367108135171
5012001321345486108137
12 Volt DC chartAmpsin WireWattsat
12V#14#12#10#8#6#4#21/02/03/0
11284131206337532
2244266103168266432675
44818335284133216337543675
6721422335689141225360450570
8961016274266108168272338427
101208.51322335384135218270342
1518068.51322355690144180228
202406.61016274267108135171
2530081322335486108137
303606.6111828457290114
404808132133546785
These are one-way distances, measured from point A to point B.
The out and back nature of electrical circuits has already been
included. For PV arrays, figure the entire run, from the panels to
the charge controller to the batteries
Cross referenceof AWG (American Wire Gauge) sizes to metric
(mm)AWGmm2AWGmm2AWGmm2AWGmm2
300.05180.756164/0120
280.08171.0425300MCM150
260.14161.5235350MCM185
240.25142.5150500MCM240
220.34124.01/055600MCM300
210.38106.02/070750MCM400
200.508103/0951000MCM500
WIRE GAUGE TABLESAmerican Wire Gauge (AWG) sizes may be
determined by measuring the diameter of the conductor (the bare
wire) with the insulation removed. Refer to the Wire gauge Diameter
Table for dimensions. When choosing wire gauge, the distance the
wire must run and the amperage it will be expected to carry must be
determined first. Refer to the Wire gauge Selection Table. Note
that you can always use thicker wire (lower gauge number) than is
recommended.METRIC-TO-AWG CONVERSION TABLE
Metric Sizemm2AWG Size
0.520
0.818
1.016
2.014
3.012
5.010
8.08
13.06
19.04
32.02
52.00
WIRE GAUGE DIAMETER TABLE
American Wire gaugeWire Diameter in inches
200.03196118
180.040303
160.0508214
140.064084
120.08080810
100.10189
80.128496
60.16202
50.18194
40.20431
30.22942
20.25763
10.2893
00.32486
000.3648
WIRE GAUGE SELECTION TABLE
Circuit AmperesCircuit WattsWire gauge (for length in feet)
6V12V6V12V3'5'7'10'15'20'25'
0 to 2.50 to 5153018181818181818
3.06183618181818181816
3.57214218181818181816
4.08244818181818181616
5.010306018181818161616
5.511336618181818161614
6.012367218181818161614
7.515459018181818141412
9.0185410818181616141412
10206012018181616141210
11226613218181616121210
12247214418181616121210
15309018018161614101010
20401202401816141210108
25501503001614121210108
5010030060012121010664
75150450900101088442
100200600120010886442
Find the amperes or watts the circuit is expected to carry on
the left and the distance the wiring must run at the top - follow
the columns until they intersect - for example, a 12 volt circuit
which is 15 feet long and carries 10 amperes should use at least 16
gauge wire.
WIRE GAUGE AND CURRENT LIMITSAWG Wire Sizes (see table
below)AWG: In the American Wire Gauge (AWG), diameters can be
calculated by applying the formula D(AWG)=.00592((36-AWG)/39)inch.
For the 00, 000, 0000 etc. gauges you use -1, -2, -3, which makes
more sense mathematically than "double nought." This means that in
American wire gage every 6 gauge decrease gives a doubling of the
wire diameter, and every 3 gauge decrease doubles the wire cross
sectional area. Similar to dB in signal and power levels. An
approximate form of this formula contributed by Mario Rodriguez is
D = .460 * (57/64)(awg +3)or D = .460 * (0.890625)(awg +3).
Metric Wire Gauges (see table below)Metric Gauge: In the Metric
Gauge scale, the gauge is 10 times the diameter in millimeters, so
a 50 gauge metric wire would be 5 mm in diameter. Note that in AWG
the diameter goes up as the gauge goes down, but for metric gauges
it is the opposite. Probably because of this confusion, most of the
time metric sized wire is specified in millimeters rather than
metric gauges.
Load Carrying Capacities (see table below)The following chart is
a guideline of ampacity or copper wire current carrying capacity
following theHandbook of Electronic Tables and Formulasfor American
Wire Gauge. As you might guess, the rated ampacities are just a
rule of thumb. In careful engineering the voltage drop, insulation
temperature limit, thickness, thermal conductivity, and air
convection and temperature should all be taken into account. The
Maximum Amps for Power Transmission uses the 700 circular mils per
amp rule, which is very very conservative. The Maximum Amps for
Chassis Wiring is also a conservative rating, but is meant for
wiring in air, and not in a bundle. For short lengths of wire, such
as is used in battery packs you should trade off the resistance and
load with size, weight, and flexibility. NOTE: For installations
that need to conform to the National Electrical Code, you must use
their guidelines. Contact your local electrician to find out what
is legal!AWG gaugeConductorDiameter InchesConductorDiameter mmOhms
per 1000 ft.Ohms per kmMaximum amps for chassis wiringMaximum amps
forpower transmissionMaximum frequency for100% skin depth for solid
conductor copper
OOOO0.4611.6840.0490.16072380302125 Hz
OOO0.409610.403840.06180.202704328239160 Hz
OO0.36489.265920.07790.255512283190200 Hz
00.32498.252460.09830.322424245150250 Hz
10.28937.348220.12390.406392211119325 Hz
20.25766.543040.15630.51266418194410 Hz
30.22945.826760.1970.6461615875500 Hz
40.20435.189220.24850.8150813560650 Hz
50.18194.620260.31331.02762411847810 Hz
60.1624.11480.39511.295928101371100 Hz
70.14433.665220.49821.63409689301300 Hz
80.12853.26390.62822.06049673241650 Hz
90.11442.905760.79212.59808864192050 Hz
100.10192.588260.99893.27639255152600 Hz
110.09072.303781.264.132847123200 Hz
120.08082.052321.5885.20864419.34150 Hz
130.0721.82882.0036.56984357.45300 Hz
140.06411.628142.5258.282325.96700 Hz
150.05711.450343.18410.44352284.78250 Hz
160.05081.290324.01613.17248223.711 k Hz
170.04531.150625.06416.60992192.913 k Hz
180.04031.023626.38520.9428162.317 kHz
190.03590.911868.05126.40728141.821 kHz
200.0320.812810.1533.292111.527 kHz
210.02850.723912.841.98491.233 kHz
220.02540.6451616.1452.939270.9242 kHz
230.02260.5740420.3666.78084.70.72953 kHz
240.02010.5105425.6784.19763.50.57768 kHz
250.01790.4546632.37106.17362.70.45785 kHz
260.01590.4038640.81133.85682.20.361107 kH
270.01420.3606851.47168.82161.70.288130 kHz
280.01260.3200464.9212.8721.40.226170 kHz
290.01130.2870281.83268.40241.20.182210 kHz
300.010.254103.2338.4960.860.142270 kHz
310.00890.22606130.1426.7280.70.113340 kHz
320.0080.2032164.1538.2480.530.091430 kHz
Metric 2.00.007870.200169.39555.610.510.088440 kHz
330.00710.18034206.9678.6320.430.072540 kHz
Metric 1.80.007090.180207.5680.550.430.072540 kHz
340.00630.16002260.9855.7520.330.056690 kHz
Metric 1.60.00630.16002260.9855.7520.330.056690 kHz
350.00560.142243291079.120.270.044870 kHz
Metric 1.4.00551.14033911140.260.043900 kHz
360.0050.127414.813600.210.0351100 kHz
Metric 1.25.004920.125428.214040.200.0341150 kHz
370.00450.1143523.117150.170.02891350 kHz
Metric 1.12.004410.112533.817500.1630.02771400 kHz
380.0040.1016659.621630.130.02281750 kHz
Metric 1.003940.1000670.221980.1260.02251750 kHz
390.00350.0889831.827280.110.01752250 kHz
400.00310.07874104934400.090.01372900 kHz
Voltage Drop Calculator by Gerald
Newtonhttp://www.electrician2.com
The following calculator calculates the voltage drop, and
voltage at the end of the wire for American Wire Gauge from 4/0 AWG
to 30 AWG, aluminum or copper wire. (Note: It just calculates the
voltage drop, consult the above table for rules-of-thumb, or your
local or national electrical code or your electrician to decide
what is legal!) Note that the voltage drop does not depend on the
input voltage, just on the resistance of the wire and the load in
amps.Top of FormSelect Copper or Aluminum Select American Wire
Gauge (AWG) Size Select Voltage Enter 1-way circuitlength in feet
(the calculation is for the round trip distance)
Enter Loadin amps
Voltage drop
Voltage at load end of circuit
Per Cent voltage drop
Wire cross section in circular mils
Bottom of Form
This chart of American Wire Gauge (AWG) wire sizes and rated
ampacities is data intended for the pleasure of our readers only.
Typographical errors, etc. are probable, since the typist is not a
professional (our CEO). Please point out errors. The data listed
are incomplete and should be used as a guideline only. Please
contact manufacturers for the latest data.
Conductor sizeIt should be common-sense knowledge that liquids
flow through large-diameter pipes easier than they do through
small-diameter pipes (if you would like a practical illustration,
try drinking a liquid through straws of different diameters). The
same general principle holds for the flow of electrons through
conductors: the broader the cross-sectional area (thickness) of the
conductor, the more room for electrons to flow, and consequently,
the easier it is for flow to occur (less
resistance).Electricalwireis usually round in cross-section
(although there are some unique exceptions to this rule), and comes
in two basic varieties: solid and stranded. Solid copperwireis just
as it sounds: a single, solid strand of copper the whole length of
thewire. Strandedwireis composed of smaller strands of solid
copperwiretwisted together to form a single, larger conductor. The
greatest benefit of strandedwireis its mechanical flexibility,
being able to withstand repeated bending and twisting much better
than solid copper (which tends to fatigue and break after
time).Wiresize can be measured in several ways. We could speak of
awire's diameter, but since its really the cross-sectionalareathat
matters most regarding the flow of electrons, we are better off
designatingwiresize in terms of area.
Thewirecross-section picture shown above is, of course, not
drawn to scale. The diameter is shown as being 0.1019 inches.
Calculating the area of the cross-section with the formula Area =
r2, we get an area of 0.008155 square inches:
These are fairly small numbers to work with, sowiresizes are
often expressed in measures of thousandths-of-an-inch, ormils. For
the illustrated example, we would say that the diameter of
thewirewas 101.9 mils (0.1019 inch times 1000). We could also, if
we wanted, express the area of thewirein the unit of square mils,
calculating that value with the same circle-area formula, Area =
r2:
However, electricians and others frequently concerned
withwiresize use another unit of area measurement tailored
specifically forwire's circular cross-section. This special unit is
called thecircular mil(sometimes abbreviatedcmil). The sole purpose
for having this special unit of measurement is to eliminate the
need to invoke the factor (3.1415927 . . .) in the formula for
calculating area, plus the need to figurewireradiuswhen you've been
givendiameter. The formula for calculating the circular-mil area of
a circularwireis very simple:
Because this is a unit ofareameasurement, the mathematical power
of 2 is still in effect (doubling the width of a circle
willalwaysquadruple its area, no matter what units are used, or if
the width of that circle is expressed in terms of radius or
diameter). To illustrate the difference between measurements in
square mils and measurements in circular mils, I will compare a
circle with a square, showing the area of each shape in both unit
measures:
And for another size ofwire:
Obviously, the circle of a given diameter has less
cross-sectional area than a square of width and height equal to the
circle's diameter: both units of area measurement reflect that.
However, it should be clear that the unit of "square mil" is really
tailored for the convenient determination of a square's area, while
"circular mil" is tailored for the convenient determination of a
circle's area: the respective formula for each is simpler to work
with. It must be understood that both units are valid for measuring
the area of a shape, no matter what shape that may be. The
conversion between circular mils and square mils is a simple ratio:
there are (3.1415927 . . .) square mils to every 4 circular
mils.Another measure of cross-sectionalwirearea is thegauge. The
gauge scale is based on whole numbers rather than fractional or
decimal inches. The larger the gauge number, the skinnier thewire;
the smaller the gauge number, the fatter thewire. For those
acquainted with shotguns, this inversely-proportional measurement
scale should sound familiar.Thetableat the end of this section
equates gauge with inch diameter, circular mils, and square inches
for solidwire. The larger sizes ofwirereach an end of the common
gauge scale (which naturally tops out at a value of 1), and are
represented by a series of zeros. "3/0" is another way to represent
"000," and is pronounced "triple-ought." Again, those acquainted
with shotguns should recognize the terminology, strange as it may
sound. To make matters even more confusing, there is more than one
gauge "standard" in use around the world. For electrical
conductorsizing, theAmericanWireGauge(AWG), also known as theBrown
and Sharpe(B&S) gauge, is the measurement system of choice. In
Canada and Great Britain, theBritish StandardWireGauge(SWG) is the
legal measurement system for electrical conductors. Otherwiregauge
systems exist in the world for classifyingwirediameter, such as
theStubssteelwiregauge and theSteel MusicWireGauge(MWG), but these
measurement systems apply to non-electricalwireuse.The
AmericanWireGauge (AWG) measurement system, despite its oddities,
was designed with a purpose: for every three steps in the gauge
scale,wirearea (and weight per unit length) approximately doubles.
This is a handy rule to remember when making roughwiresize
estimations!Forverylargewiresizes (fatter than 4/0), thewiregauge
system is typically abandoned for cross-sectional area measurement
in thousands of circular mils (MCM), borrowing the old Roman
numeral "M" to denote a multiple of "thousand" in front of "CM" for
"circular mils." The followingtableofwiresizes does not show any
sizes bigger than 4/0 gauge, becausesolidcopperwirebecomes
impractical to handle at those sizes. Strandedwireconstruction is
favored, instead.
WIRE TABLE FOR SOLID, ROUND COPPER CONDUCTORS
Size Diameter Cross-sectional area Weight AWG inches cir. mils
sq. inches lb/1000 ft
=============================================================== 4/0
-------- 0.4600 ------- 211,600 ------ 0.1662 ------ 640.5 3/0
-------- 0.4096 ------- 167,800 ------ 0.1318 ------ 507.9 2/0
-------- 0.3648 ------- 133,100 ------ 0.1045 ------ 402.8 1/0
-------- 0.3249 ------- 105,500 ----- 0.08289 ------ 319.5 1
-------- 0.2893 ------- 83,690 ------ 0.06573 ------ 253.5 2
-------- 0.2576 ------- 66,370 ------ 0.05213 ------ 200.9 3
-------- 0.2294 ------- 52,630 ------ 0.04134 ------ 159.3 4
-------- 0.2043 ------- 41,740 ------ 0.03278 ------ 126.4 5
-------- 0.1819 ------- 33,100 ------ 0.02600 ------ 100.2 6
-------- 0.1620 ------- 26,250 ------ 0.02062 ------ 79.46 7
-------- 0.1443 ------- 20,820 ------ 0.01635 ------ 63.02 8
-------- 0.1285 ------- 16,510 ------ 0.01297 ------ 49.97 9
-------- 0.1144 ------- 13,090 ------ 0.01028 ------ 39.63 10
-------- 0.1019 ------- 10,380 ------ 0.008155 ----- 31.43 11
-------- 0.09074 ------- 8,234 ------ 0.006467 ----- 24.92 12
-------- 0.08081 ------- 6,530 ------ 0.005129 ----- 19.77 13
-------- 0.07196 ------- 5,178 ------ 0.004067 ----- 15.68 14
-------- 0.06408 ------- 4,107 ------ 0.003225 ----- 12.43 15
-------- 0.05707 ------- 3,257 ------ 0.002558 ----- 9.858 16
-------- 0.05082 ------- 2,583 ------ 0.002028 ----- 7.818 17
-------- 0.04526 ------- 2,048 ------ 0.001609 ----- 6.200 18
-------- 0.04030 ------- 1,624 ------ 0.001276 ----- 4.917 19
-------- 0.03589 ------- 1,288 ------ 0.001012 ----- 3.899 20
-------- 0.03196 ------- 1,022 ----- 0.0008023 ----- 3.092 21
-------- 0.02846 ------- 810.1 ----- 0.0006363 ----- 2.452 22
-------- 0.02535 ------- 642.5 ----- 0.0005046 ----- 1.945 23
-------- 0.02257 ------- 509.5 ----- 0.0004001 ----- 1.542 24
-------- 0.02010 ------- 404.0 ----- 0.0003173 ----- 1.233 25
-------- 0.01790 ------- 320.4 ----- 0.0002517 ----- 0.9699 26
-------- 0.01594 ------- 254.1 ----- 0.0001996 ----- 0.7692 27
-------- 0.01420 ------- 201.5 ----- 0.0001583 ----- 0.6100 28
-------- 0.01264 ------- 159.8 ----- 0.0001255 ----- 0.4837 29
-------- 0.01126 ------- 126.7 ----- 0.00009954 ---- 0.3836 30
-------- 0.01003 ------- 100.5 ----- 0.00007894 ---- 0.3042 31
------- 0.008928 ------- 79.70 ----- 0.00006260 ---- 0.2413 32
------- 0.007950 ------- 63.21 ----- 0.00004964 ---- 0.1913 33
------- 0.007080 ------- 50.13 ----- 0.00003937 ---- 0.1517 34
------- 0.006305 ------- 39.75 ----- 0.00003122 ---- 0.1203 35
------- 0.005615 ------- 31.52 ----- 0.00002476 0.09542 36 -------
0.005000 ------- 25.00 ----- 0.00001963 0.07567 37 ------- 0.004453
------- 19.83 ----- 0.00001557 0.06001 38 ------- 0.003965 -------
15.72 ----- 0.00001235 0.04759 39 ------- 0.003531 ------- 12.47
---- 0.000009793 0.03774 40 ------- 0.003145 ------- 9.888 ----
0.000007766 0.02993 41 ------- 0.002800 ------- 7.842 ----
0.000006159 0.02374 42 ------- 0.002494 ------- 6.219 ----
0.000004884 0.01882 43 ------- 0.002221 ------- 4.932 ----
0.000003873 0.01493 44 ------- 0.001978 ------- 3.911 ----
0.000003072 0.01184
For some high-current applications, conductor sizes beyond the
practical size limit of roundwireare required. In these instances,
thick bars of solid metal calledbusbarsare used as conductors.
Busbars are usually made of copper or aluminum, and are most often
uninsulated. They are physically supported away from whatever
framework or structure is holding them by insulator standoff
mounts. Although a square or rectangular cross-section is very
common for busbar shape, other shapes are used as well.
Cross-sectional area for busbars is typically rated in terms of
circular mils (even for square and rectangular bars!), most likely
for the convenience of being able to directly equate busbar size
with roundwire. REVIEW: Electrons flow through large-diameter wires
easier than small-diameter wires, due to the greater
cross-sectional area they have in which to move. Rather than
measure smallwiresizes in inches, the unit of "mil" (1/1000 of an
inch) is often employed. The cross-sectional area of awirecan be
expressed in terms of square units (square inches or square mils),
circular mils, or "gauge" scale. Calculating square-unitwirearea
for a circularwireinvolves the circle area formula: Calculating
circular-milwirearea for a circularwireis much simpler, due to the
fact that the unit of "circular mil" was sized just for this
purpose: to eliminate the "pi" and the d/2 (radius) factors in the
formula. There are (3.1416) square mils for every 4 circular mils.
Thegaugesystem ofwiresizingis based on whole numbers, larger
numbers representing smaller-area wires and vice versa. Wires
thicker than 1 gauge are represented by zeros: 0, 00, 000, and 0000
(spoken "single-ought," "double-ought," "triple-ought," and
"quadruple-ought." Very largewiresizes are rated in thousands of
circular mils (MCM's), typical for busbars andwiresizes beyond 4/0.
Busbarsare solid bars of copper or aluminum used in high-current
circuit construction. Connections made to busbars are usually
welded or bolted, and the busbars are often bare (uninsulated),
supported away from metal frames through the use of insulating
standoffs.
Wire Size
Recently, there has been numerous questions on this board
concerning the proper type or size of AC power cable to use with
different amounts of equipment. It is very important to use the
correct size cable to insure all the power will be available to
your equipment and there is no danger of a fire or short from your
cables.Here is a Cable/Current table to help you select the proper
one to use in your application.Wire Size (AWG)2 Conductor3
Conductor4 Conductor
1030Amp2520
12252016
14181512
1613108
181076
Notice that the smaller the AWG number, the more current it can
handle. All Extension Cords are required to list the wire gauge.
That will tell you the amount of current they can safely handle.The
wire in the above example is Copper type and of the same
temperature rating. All currents listed are for Ambient
temperature. Keep in mind that there are also many different type
of insulation material that will determine the temperature rating.
The wire may not be pure copper but an alloyed of aluminum, nickel,
tin and copper.Standard cable, as used in home and general
construction, is classified by the wire size, number of wires,
insulation type and dampness condition of the wire
environment.Example: a cable with the code "12/2 with Ground Type
UF 600V (UL)" has the following specifications:1. Wire size is 12
gauge (minimum required size for homes today).
2. The "/2" indicates there are two wires in the cable.
3. "Ground" indicates there is a third wire in the cable to be
used as a grounding wire.
4. "Type UF" indicates the insulation type and acceptable
dampness rating.
5. "600V" means the wire is rated at 600 volts maximum.
6. "UL" indicates the wire has been certified by Underwriters
Laboratory to be safe.
Standard wire color codes are very different between electronic
circuitry and household 110 Volt AC wiring.
Household wiring (or other AC applications in the 100+ volt
range) use the following color codes:BLACK"Hot" wire. Connected to
Brass colored terminal.GREEEN"Ground" wire. Also called chassis
ground.RED"Traveler" wire. Used for 3-ways switches.WHITE "Neutral"
wire. Connected to silver colored terminal.VOLTAGE DROP vs. WIRE
SIZEVoltage drop is the amount of voltage lost over the length of a
circuit. Voltage drop changes as a function of the resistance of
the wire and should be less than 2% if possible. If the drop is
greater than 2%, efficiency of the equipment in the circuit is
severely decreased and life of the equipment will be decreased. As
an example, if the voltage drop on an incandescent light bulb is
10%, the light output of the bulb decreases over 30%!Voltage drop
can be calculated using Ohmss Law, which is:Voltage Drop = Current
in amperes x Resistance in ohms.For example, the voltage drop over
a 200 foot long, #14 copper wire, power line supplying a 1000 watt
floodlight is calculated as follows:Current = 1000watts/120volts =
8.33 amperes
Resistance of #14 copper wire = 2.58ohms/1000feet
Resistance of powerline=2 x 200ft x 0.00258ohms/ft=1.032ohms
Voltage drop = 8.33 amperes x 1.032 ohms = 8.60 volts
Percent voltage drop = 8.60volts/120volts = 7.2%
The 7.2% drop is over the maximum 2% so either the wattage of
the bulb must be decreased or the diameter of the wire must be
increased (a decrease in wire gauge number). If #9 copper wire were
used in the above example, the voltage drop would have only been
2.2%.A more commonly used method of calculating voltage drop is as
follows:K x 2 x Wire length in ft. x Current in amperes
Voltage Drop
=-------------------------------------------------
Wire area in circular mils
K = Specific resistivity in ohm circular mils/footK = 11 for
copper wire loaded at 50% of capacity.K = 12 for copper wire loaded
to 50-100% capacity.K = 18 for aluminum wireUsing values from the
Ohms Law example above: #14 copper wire has an area of 4110
circular mils, then voltage drop = (11 x 2 x 200 x 8.33) / 4110 =
8.92volts = 8.92volts/120volts = 7.4%.An interesting corollary to
the above example is that if the line voltage doubles (240 volts
instead of 120volts), the voltage drop decreased by a factor of 4.
That means that a line can carry the same power 4 times further!
Higher voltage lines are more efficient. Thats why voltage is so
high (50,000volts) for power transmission lines.I hope this help
explain many questions about AC power and cables.
WIRING TABLE NECAWG American Wire Gauge to mm2WIRING
Short TableAWGmm2AWGmm2AWGmm2AWGmm2
300.05180.756164/0120
280.08171.0425300MCM150
260.14161.5235350MCM185
240.25142.5150500MCM240
220.34124.01/055600MCM300
210.38106.02/070750MCM400
200.508103/0951000MCM500
AWG American Wire Gauge / Diameter / ResistanceUsed in the
United States and other countries as a standard method of denoting
wire diameter. The higher the number the thinner the wire. Thicker
wire is generally capable of carrying larger amount of current over
greater distances with less loss (though there are other things
that cause current loss in wire). Sometimes the loss of cables is
rated in Ohms per one thousand feet and for a particular type of
wire the lower gauges (larger wires) have less resistance to
current flow. (Sweetwater Archive)See:Maximum current load
AWG American Wire Gauge
TableAWGDiameterDiameterSquareResistanceResistance
mminch mm2ohm/kmohm/1000 feet
460,040,001313700
440,050,00208750
420,060,00286070
410,070,00394460
400,080,00503420
390,090,00642700
380,100,00400,00782190
370,110,00450,00951810
360,130.0050,0131300445
350,140,00560,0151120
340,160.00630,020844280
330,180,00710,026676
AWGDiameterDiameterSquareResistanceResistance
mminch mm2ohm/kmohm/1000feet
320,200.0080,031547174
300,250.010,049351113
280,330.0130,08232.070.8
270,360.0180,09617854.4
260,410.0160,1313743.6
250,450,01790,16108
240,510.020,2087,527.3
220,640.0250,3351,716.8
200,810.0320,5034,110.5
181,020.040,8221,96.6
161,290.0511,313,04.2
141,630.0642,08,542.6
AWGDiameterDiameterSquareResistanceResistance
mminch mm2ohm/kmohm/1000feet
131,800,07202,66,76
122,050.0813,35.41.7
102.590.1025.263.41.0
83.250.1288..2962.20.67
64.1150.16513.2981.50.47
45.1890.204321.150.80.24
26.5430.257633.620.50.15
17.3480.289342.410.40.12
08.2520.32553.490.310.096
009.2660.36567.430.250.077
00010.400.409685.010.20.062
000011.6840.460107.2190.160.049
Metric GaugeMetric GaugeDiameterSquareResistance
mm mm2ohm/m
50,50,200,0838
60,60,280,0582
80,80,50,0328
101,00,80,0210
141,41,540,0107
161,62,00,00819
202,03,140,00524
252,54,910,00335
US National Electrical Codemaximum Amperage
AWG Wire SizeTwo Current Carrying ConductorsThree Current
Carrying Conductors
AmpereAmpere
18710
161013
141518
122025
102530
83540
64555
46070
28095
Amperage for Power Extension Cords (US)(always uncoil the cord
completely under oreration)
14 / 3 AWG Cable
LengthAmperage
50'15 A
100'13 A
150'8 A
200'6 A
250'5 A
300'4 A
12 / 3 AWG Cable
LengthAmperage
50'15 A
100'15 A
150'13 A
200'10 A
250'7 A
300'6 A
10 / 3 AWG Cable
LengthAmperage
50'15 A
100'15 A
150'15 A
200'15 A
250'13 A
300'10 A
AWG / Amperage and ConnectorsAWGmax. AmperageConnector
0000 (4/0)300 ACamLock
000 (3/0)260 ACamLock
00 (2/0)225 ACamLock
0 (1/0)195 ACamLock
2125 AC-Way (50')
490 AC-Way (50')
670 AJoy&Cabtire (25'&50')
850 AJoy&Cabtire (25'&50')
1030 AJoy&Cabtire (25'&50')
1220 AA.C. Wire (25'&50')
1415 AA.C. Wire (25'&50')
1610 AA.C. Wire
Amperage and Insulation HeatAmperage that is needed to heat up
the insulation to a certain temperature (Copper Cable / different
Insulation Materials) in free air (30C)
AWGPOLYPROPYLENE, POLYETHYLENE,(high density)at 90CPVC
(irradiated), NYLONat 105CKAPTON, TEFLON, SILICONEat 200C
303 A3 A4 A
284 A4 A6 A
265 A5 A7 A
247 A7 A10 A
229 A10 A13 A
2012 A13 A17 A
1817 A18 A24 A
1622 A24 A32 A
1430 A33 A45 A
1240 A45 A55 A
1055 A58 A75 A
870 A75 A100 A
6100 A105 A135 A
4135 A145 A180 A
2180 A200 A240 A
Basic wire sizing guide for US 120 and 240 voltsUseful info:
# = American Wire Gauge (AWG), the lower the number the larger
the wire guage."Service cable" is large insulated stranded copper
cable (usually refers to single #4 wire and up).
Most house hold circuits (Typically 15 - 30 amp) can safely
handle 95% to 100% of its max rating - but only for an hour or so
at a time. Loads that require long periods of 'on' time (like an
air conditioner, ballasts, etc) should not exceed 80% to 85% of the
max rated load of the wire/cable. The known safe capacity that the
National Electric Code (NEC) recommends at 100%, is actually 80% of
load.
99.9% of the time when you get into "insulated" #8 and bigger
wire, its most likely going to be stranded (just like its big
sister "Service cable"). You can usually get your basic sheathed
xx/2 and xx/3 cable up to 6 guage. If you need larger than #8 or #6
though, you will have to buy service or "service type" cable. This
can cause two problems. One: very high cost on long runs. Two: the
cable might not fit the appropriately-sized breaker on a long run.
This is why its wise to opt for putting your ballast on 240V when
2400+ watts of light power is needed on a single circuit.
#4 and above = Cable1/0 and 2/0 are Service cable
120V (US) (@ 80% max load)(50ft run or less)GaugeAmpsWatts
#1691080
#14121440
#12161920
#10242880
#8323840
#6404800
#4485760
240V (US) (@ 80% max load)(50ft run or less)GaugeAmpsWatts
#1692160
#14122880
#12163840
#10245760
#8327680
#6409600
#44811520
Run LengthAmps100150150' - 200'200- 250'250'250' - 300'300300' -
400'400'400-500500'
12#12#10#8#6#4
16#10#8#6#4#2
24#8#6#4#2
32#6#4#2#1#1/0
40#6#4#2#1#1/0#2/0
Note:
For every extra 50 feet of cable/wire up to #8 normally you
upgrade to the next size, consult you local codes if your unsure
about double and triple length runs.
Ex: #6 is sometimes mandatory for a 200 foot 12 amp run but can
be used up to 300 feet on a 12 amp circuit.
Note:Each time an additional plug is used in line of the run
using 80% safe load, subtract an additional 2% from the over all
power usage (80% to 78%).
Ex: One plug into the wall counts as your one 'free' plug.
WARNING: extension cords ARE included into the total length from
breaker box (+25 feet and one gauge up), if intended for continuous
use at said MAX safe power usage.
In addition, you need to make sure you getting what is actually
equal to said gauge (if your making you own cord from something
like SJO cable).
Recently, I have found that some places go by size and not
current. A 12 gauge standard wire is actually the size of 10 gauge
solid. This is to make up for it not being a solid connector. Bring
something with you to compare wire size with what's printed/stamped
on the sheeting. It should be one gauge bigger in size than what's
on the sheeting.Ex: If you have a 1000W light and are using a 12
amp circuit, you should use a 15amp #12 extension cord no longer
than 25 feet.
This info isnt complete and probably doesnt apply to many, cuz
if your thinking this big you should already have a general
understanding of codes and loads.
#4 (approx 65-75A each) used for 100-115 amp service#2 (approx
90A each) used for 125-150 amp service#1/0 (approx 150A each) used
for 200 amp service#2/0 (approx 175A each) typically for industrial
or vary long run with a large load. 300-350 amp service#0/3 (approx
200A each) typically for industrial or vary long run with a large
load. 400 amp service
Service cable is specifically designed for extra service lines
and or extra long (In structure or over-head) runs. 1/0 Gauge I
believe is the only service cable (or cable) sold connected as x/3
(retail), provides a path fore both hots, the neutral and
ground.Please specify wire / insulation /cable type. Tables fairly
meaningless without.There is no accurate rule of thumb for distance
/ wire upsizing. I'm afraid one must do the math here, particularly
with the price of wire what it is."Recently, I have found that some
places go by size and not current. A 12 gauge standard wire is
actually the size of 10 gauge solid. This is to make up for it not
being a solid connector. Bring something with you to compare wire
size with what's printed/stamped on the sheeting. It should be one
gauge bigger in size than what's on the sheeting."Stranded wire is
physically larger, but uses the same amount of copper. Carries the
same amount of current. Solid wire dimension gauges are fairly
worthless for measuring stranded wire.Stranded wire exhibits better
electrical performance in AC circuits.
This page is to provide a single place to look to for what the
safe rated capacities of various size wires in general use. These
are general guidelines - check with the wire manufacturer or
standards body controlling your installation for any additional
specifications. Keep in mind that temperature and environment have
a dramatic effect on these ratings, and that for wiring it's much
better to err on the side of too large a wire than too small.This
page started as a page for 12V DC automotive use, but has grown
over time to include a more general set of information on wire
sizing. I've tried to add some basic explanations of what matters
when sizing a wire and to avoid using too many details specific to
certain applications. The actual formulas used to figure this out
can be very complex - for example the National Electrical Code
specifies the wire sizes to be used in excruciating detail based on
years of actual research on what happens to wires in The Real
World. Keeping up with all those details can be very hard, but the
basic principles are pretty straightforward. My goal for this page
is to expose you to those basic concepts, and at the end to give a
basic "rule of thumb" chart for folks to start out with.This page
was created to help explain concepts and give an overview of wire
capacity and what is factored into deciding on the wire size to use
in a given application. This page shouldnotto be considered an
authoritative source of exact numbers on what wire size to use.
Consult other sources such as wiring codes and manufacturers
recommendations on the piece of equipment you are installing for
more details. I am not telling you what wire size to use - the
information here is provided as-is and without any guarantee as to
it's accuracy or completeness. Any issues caused by the use of this
information are not my fault - be smart, use common sense, and use
this information at your own risk.Measuring Wire CapacityThe amount
of power a wire can safely carry is related to how hot it can
safely get. All wires have resistance, and as power flows through a
wire that resistance causes heat - and it can be quite a bit of
heat. The more power you put through a wire, the hotter it gets.
Insulation breaks down as it gets hot, and at some point it will
melt away leaving the wire exposed to whatever is around it - other
wires, grounded metal, people, etc. The heat can even be enough to
start a fire in the surrounding material in some cases. Electrical
fires are nasty and tend to start in the hardest to reach places -
where the most heat builds up back in dark corners and tight
spaces. This is why using the right size wires is important for
your safety and for safety of others using your wiring work.In some
respects, the capacity of a wire is actually best measured in
watts, not amperage. Why? Because a watt is a unit or power that is
a combination of amperage (volume), voltage (pressure), and
resistance to the power flowing through that wire. Watts measure
the amount of power (aka, heat) a wire can safely dissipate.
However, most wire charts are done in amps. This is unfortunate
because it means the wire chart is sort of assumed to be at a
single voltage level. For most usage, this is fine because the
chart has an assumed usage. As an example, charts for amperage
ratings of of various sizes wires for 110V AC house current charts
are popular and reasonably well-known. On the other hand, the
amperage ratings are very different for common/typical 12V DC
automotive usage. For example, a 12 gauge wire is commonly rated at
20A for 110V AC home usage, but in automotive 12V DC use 12 gauge
wire is commonly used for circuits carrying 60A! A prime example
would be the main charging wire from the alternator to the battery
and out to the main electrical circuits of the car. I thought I had
a satisfactory explanation posted here previously, but a few folks
took aim at it and blew gaping holes in my understanding - without
actually explaining what I was trying to understand or explain
here. As of yet, I have not gotten a satisfactory explanation for
this discrepancy. No one I've talked to as of yet has been able to
explain it to me, but if you think you know the magic answer,please
let me know. Maybe I'm missing something obvious. Maybe I'm just
not understanding this as well I as think I am. Who knows... At any
rate, the chart below reflects the difference in 110V AC vs. 12V DC
usage, even though I'm still at a loss to explain the
details.Remember, if in doubt, it's always better to put in too big
of a wire than too small of a wire.Stranded vs. Solid WireThis one
is a bit of a mind-boggler, but it's important. When electricity
flows through a wire, it mostly flows on the surface of the wire,
not through the middle. This effect is more pronounced on high
frequency AC than it is on DC or low frequency AC. This means that
a "wire" of a given size that made up of many smaller strands can
carry more power than a solid wire - simply because the stranded
wire has more surface area. This is one reason why battery cables
in your car and welding cables are made up of many very fine
strands of smaller wire - it allows them to safely carry more power
with less of that power being dissipated as heat. However, this
"skin" effect is not as pronounced in a typical 12V DC automotive
application, and the wire and cable used there is stranded for
flexibility reasons.When looking at a chart or description of wire
capacity, take note of whether it is referring to stranded or solid
wire - some charts may not specify but instead assume a default
based on the typical wiring used in a given application. For
example, almost all automotive wiring is stranded while almost all
home wiring is solid. For most applications, flexibility or the
lack thereof will be more important, but for very high frequency AC
applications, stranded wire might be a requirement.Open Air vs.
Bundles and/or ConduitsHeat is the primary determiner of the
maximum amount of power any wire can carry, and the ability of that
wire to dissipate that heat has a large impact on the final rating.
Wires that are run in bundles (such as in a wiring harness or
wiring conduit) cannot dissipate heat as easily as a single wire
run in "open air", and as such must be "de-rated" to less than
their maximum value to account for this. Also, wires that are run
in areas that are unusually hot (such as in an attic or in an
engine compartment) may need similar de-ratings. If both situations
are encountered together (bundled wires in an unusually hot
environment) then you need to de-rate forbothfactors and the
capacity is further reduced.In a car, almost all wiring is run in a
bundle, and much of it runs near the engine. In a house, a lot of
wiring typically runs through the attic, often in a bundle/group
and sometimes in a conduit. Pay attention to this and size your
wires appropriately.Wire LengthSince all wires have resistance, the
longer the wire, the greater the resistance. This means that for
longer wiring runs you need to use a larger wire to compensate.
This phenomenon is often referred to as "voltage drop", and for
lower voltage automotive systems, the loss of 2V or even 1V can be
significant. On longer wire runs, plan on using a larger size wire.
There are specific voltage drop calculations that depend on the
wire size in use, the length of the wire, the load applied, and the
voltage in use. The National Electric Code has tons of charts for
this, but there's anifty online voltage drop calculatorthat one of
my readers pointed out to me that does 120V AC as well as 12V DC -
and even 6V DC. You'd be surprised at some of the voltage drops you
can find just form the wiring in use, so experiment with the
calculator a bit to see if it's worth going to the next highest
size wire in your application. On automotive applications of only
12V, losing a single volt of power in the wire is a whopping 8%
loss, so it can be a big deal for voltage critical applications
like your headlights where more voltage = more light. Kudos to Ron
White for providing me with the link to thatcalculator, and kudos
to the folks over atPowerStream.comfor putting that calculator and
other data online.Duration of UsageSome electrical loads are
continuous for long periods of times (like a light in your house or
the headlights on your car) and some are much more intermittent
(like a garbage disposal in your house or the starter in your car).
This affects the wire size used - the longer a wire is in use, the
more heat it will tend to retain. A wire for something that is only
used for short periods (like the starter in your car) does not need
quite as large of a wire as something that will be in use for very
long periods of time. This means that for long-duration uses, you
must de-rate the wire even further and use a larger size.Electrical
CalculationsThere are four basic units of measurement for
electricity: Power, measured in Watts, commonly referred to as "P"
Current, measured in Amps, commonly referred to as "I" Voltage,
measured in Volts, commonly referred to as "V" Resistance, measured
in Ohms, commonly referred to as "R"There are a number of formulas
that relate each of these four things - they all change in
relationship to one another such that if you know any two you can
calculate the other two. Lots of folks on the Internet have easy-to
use calculators that allow you to do this online
-http://www.sengpielaudio.com/calculator-ohm.htmis one. The formula
wheel below was on their website and presents the info in a pretty
easy to understand format.
Capacity ChartThis chart is a simple "max capacity" chart for a
short wire run. Increase the wire size for long runs - for example
the wires running to the back of a vehicle to power the taillights
may need to be one size larger to account for the
length.Gauge110V12V
225A5A
207.5A8A
1810A10A
1613A20A
1417A40A
1223A60A
1033A100A
846A150A
660A??A
480A??A
2100A??A
1125A??A
0150A??A
Chart Notes This 110V column in this chart was provided by one
of my readers and according to him it is based on the data in The
Howard W. Sams Engineering Staff fifth edition 1983 for stranded
copper wire when used in a conduit or bundle. (Open air ratings
would be higher, solid copper wire ratings might be slightly
lower.) This data seems in line with commonly accepted usage for
120/220V home electrical wiring. The 12V column is based on various
sources I have found across the Internet combined with the accepted
usage in various vehicles I have worked on. I am generally a bit
skeptical of the max capacity the sources I found claimed for some
of the smaller wire sizes. For example, 16 gauge wire is mighty
thin to run 20A through for even a short distance, and this chart
is aconservativeinterpretation of the data I found out there. Some
data had the max capacity even higher than this - yikes! The values
here for 12V usage are not yet certified to be correct/valid/safe -
they are my ballpark figures based on what I believe to be true
based on what I have learned. Consult other sources of information
for your specific application for more details.
Wire Type and Sizing Considerations
Written by Richard
Friday, 10 August 2007
Wire Type and Sizing ConsiderationsWhen a professional
electrician looks at a job to wire a house or a new circuit in any
structure the primary consideration in the wiring job is the size
and type of wire to be used for job. The same for a plumber when
looking at a job the plumber will size the pipes based on the
number of gallons needed to carry the proper amount of water to its
destination. If the pipe is too small then the water needed will
not reach its destination. This is almost the same for electrical
wire except under-sizing electrical wire is dangerous. Electrical
wire carries voltage but it is the current rating of the power
loads which is the primary factor in determining the size and type
of wire to be used for the job. The current or amps, like the water
pipe, is measured by how much flow there is in the wire. If the
wire is too small and the flow too fast then wire gets hot. If it
gets too hot then the insulation melts and a dangerous condition
exists. If the wire runs for a prolonged period of time at a higher
than rated temperature there are also corrosive effects at terminal
connections. Eventually the corrosion and the excessive heat will
cause the wire to become brittle. Solid wire will become brittle
enough to eventually break off completely while stranded wire will
lose strands one strand at a time from this effect. This causes the
wire to become smaller and the heat increases. Eventually the
current becomes too much for the wire and it breaks off again
creating a dangerous condition. The equipment or device being
supplied electricity from this wire, when it breaks, ceases to
function while a live wire is hanging inside a control panel or
other panel. This is why it is very important to properly size
electrical wires for any type of electrical work and not to
overload existing circuits in homes and businesses. Imagine a wire
inside of a wall getting too hot and the insulation melting. This
creates a dangerous electrical situation and also is a fire
hazard.
Wire Type for the ApplicationOne other consideration in
electrical wiring is choosing the right wire type. This usually
refers to the insulation of the wire and its temperature rating.
Selecting the approapiate insulation type and temperature rating is
important and depnds on the environment and application of where
the wire will be used. Romex is an all purpose wire almost used
exclusively in residential wiring where the heat is not excessive
and the wire is not subject to damage. Each specific type of wire
has its own application and temperature rating and must be used in
accordance with the NEC (National Electrical Code). Some wire is
rated for direct burial underground while other wire is not rated
for direct burial and must be used on conduit when run underground.
Always refer to the NEC or your local electrical inspector for
rules pertaining to the type of wire and the application. Wire
Sizing ChartThe following chart shows the proper wire size or wire
guage ( awg ) for the desired current or amperage.* The national
electric code (NEC) specifies that the over-current protection
device (breaker, fuse, or motor over-load) not exceed 15A for 14
AWG wire, 20A for 12 AGW wire, and 30A for 10 AGW wire.Maximum
Ampacity for Copperand Aluminum Wire
Wire SizeCopperAluminum
167(75C)194(90C)167(75C)194(90C)
*1420 (*15)25.
*1225 (*20)302025
*1035 (*30)403035
850554045
665755060
485956575
211513090100
Wire Size and Amp Ratings
Wire Gauge SizeCopperAluminum
60C(140F)75C(167F)90C(194F)75C(167F)90C(194F)
NM-BTHWTHWN-2THWXHHW-2
UF-BTHWNTHHNTHWNTHHN
SEXHHW-2SETHWN-2
USEUSE-2USE
XHHWXHHW
14151515------
122020201515
103030302525
84050554045
65565755060
47085956575
3851001107585
29511513090100
1---130150100115
1/0---150170120135
2/0---175195135150
3/0---200225155175
4/0---230260180205
250---255290205230
300---285320230255
350---310350250280
500---380430310350
600---420475340385
750---475535385435
1000---545615445500
WARNING!Installation of electrical wire can be hazardous, if
done improperly, can result in personal injury or property damage.
For safe wiring practices, consult the National Electrical Code and
your local building inspector.
American Wire Gauge Chart
AWGDIAMETERAREAWEIGHT(KILOGRAMS PER METER)TURNS OF WIRE(PER
INCH)
0000 (4/0)0.46" (11.7mm)212 kcmil (107mm)0.9532.17
000 (3/0)0.41" (10.4mm)168 kcmil (85 mm)0.7562.44
00 (2/0)0.365" (9.27mm)133 kcmil (67.4 mm)0.5992.74
00.325" (8.25 mm)106 kcmil (53.5 mm)0.4753.08
10.289" (7.35 mm)83.7 kcmil (42.4 mm)0.3773.46
20.258" (6.54 mm)66.4 kcmil (33.6 mm)0.2993.88
30.229" (5.83 mm)52.6 kcmil (26.7 mm)0.2374.36
40.204" (5.19 mm)41.7 kcmil (21.2 mm)0.1884.89
50.182" (4.62 mm)33.1 kcmil (16.8 mm)0.1495.5
60.162" (4.12 mm)26.3 kcmil (13.3 mm)0.1186.17
70.144" (3.66 mm)20.8 kcmil (10.5 mm)0.09386.93
80.128" (3.26 mm)16.5 kcmil (8.37 mm)0.07447.78
90.114" (2.91 mm)13.1 kcmil (6.63 mm)0.0598.74
100.102" (2.59 mm)10.4 kcmil (5.26 mm)0.04689.81
110.0907" (2.30 mm)8.23 kcmil (4.17 mm)0.037111
120.0808" (2.05 mm)6.53 kcmil (3.31 mm)0.029412.4
130.0720" (1.83 mm)5.18 kcmil (2.62 mm)0.023413.9
140.0641" (1.63 mm)4.11 kcmil (2.08 mm)0.018515.6
150.0571" (1.45 mm)3.26 kcmil (1.65 mm)0.014717.5
160.0508" (1.29 mm)2.58 kcmil (1.31 mm)0.011619.7
170.0453" (1.15 mm)2.05 kcmil (1.04 mm)0.0092222.1
180.0403" (1.02 mm)1.62 kcmil (0.823 mm)0.0073224.8
190.0359" (0.912 mm)1.29 kcmil 0.653 mm)0.005827.9
200.032" (0.812 mm)1.02 kcmil 0.518 mm)0.004631.3
210.0285" (0.723 mm)0.810 kcmil (0.410 mm)0.0036535.1
220.0253" (0.644 mm)0.642 kcmil (0.326 mm)0.0028939.5
230.0226" (0.573 mm)0.509 kcmil (0.258 mm)0.0022944.3
240.0201" (0.511 mm)0.404 kcmil (0.205 mm)0.0018249.7
250.0179" (0.455 mm)0.320 kcmil (0.162 mm)0.0014455.9
260.0159" (0.405 mm)0.254 kcmil (0.129 mm)0.0011462.7
270.0142" (0.361 mm)0.202 kcmil (0.102 mm)0.00090870.4
280.0126" ( 0.321 mm)0.16 kcmil (0.081 mm)0.0007279.1
290.0113" (0.286 mm)0.127 kcmil (0.0642 mm)0.00057188.8
300.01" (0.255 mm)0.101 kcmil (0.0509 mm)0.00045399.7
310.00893" (0.227 mm)0.0797 kcmil (0.0404 mm)0.000359112
320.00795" (0.202 mm)0.0632 kcmil (0.032 mm)0.000285126
330.00708" (0.18 mm)0.0501 kcmil (0.0254 mm)0.000226141
340.00630" (0.16 mm)0.0398 kcmil (0.0201 mm)0.000179159
350.00561" (0.143 mm)0.0315 kcmil (0.0160 mm)0.000142178
360.005" (0.127mm)0.025 kcmil (0.0127 mm)0.000113200
370.00445" (0.113 mm)0.0198 kcmil (0.01 mm)0.0000893225
380.00397" (0.101 mm)0.0157 kcmil (0.00797 mm)0.0000708252
390.00353" (0.0897 mm)0.0125 kcmil (0.00632 mm)0.0000562283
400.00314" (0.0799 mm)0.00989 kcmil (0.00501 mm)0.0000445318
Which wire gauges am I most likely to encounter?Even though 44
different wire diameters are recognized within the AWG standard,
theyre not all widely used, and most people are likely to encounter
only a small range of them. Below are a few common cable types we
use ever day, as well as the AWG sizes that correspond to them:
Speaker Cable: 14 and 16 AWG Coaxial Cable(for cable TV and a few
Ethernet applications): 18 and 20 AWG Cat 5, Cat 5e, and Cat 6
cables(for LANs and Ethernet): 24 AWG Telephone Cable: 22 28
AWG
For more great information on American Wire Gauge, including
wire diameter formula, check outWikipedia's section on AWG.