Wire Size Chart. Use The Right Size For The Load!!

by gadget
Monday, April 05 2004 @ 05:00 PM PDT
Views: 3,223
Posted in Gadget's Toolbox

12 Volt Wiring Reference Guide

The size of the wire you're using must be large enough to carry the maximum current expected without undue voltage losses. All wire has a certain amount of resistance to the flow of current. This resistance causes a drop in the voltage from the source to the load. Voltage drops cause inefficiencies, especially in low voltage systems (12V or less).

The wire sizing guide below provides the minimum wire size needed to limit voltage drops to 5% at a given distance in a 12V system. If you want to limit your losses to 2% simply divide the distance by 2.5.

AWG gauge	Diameter Inches	Diameter mm	Ohms per 1000 ft	Ohms per km	Maximum amps for chassis wiring	Maximum amps for power transmission
OOOO	0.46	11.684	0.049	0.16072	380	302
OOO	0.4096	10.40384	0.0618	0.202704	328	239
OO	0.3648	9.26592	0.0779	0.255512	283	190
0	0.3249	8.25246	0.0983	0.322424	245	150
1	0.2893	7.34822	0.1239	0.406392	211	119
2	0.2576	6.54304	0.1563	0.512664	181	94
3	0.2294	5.82676	0.197	0.64616	158	75
4	0.2043	5.18922	0.2485	0.81508	135	60
5	0.1819	4.62026	0.3133	1.027624	118	47
6	0.162	4.1148	0.3951	1.295928	101	37
7	0.1443	3.66522	0.4982	1.634096	89	30
8	0.1285	3.2639	0.6282	2.060496	73	24
9	0.1144	2.90576	0.7921	2.598088	64	19
10	0.1019	2.58826	0.9989	3.276392	55	15
11	0.0907	2.30378	1.26	4.1328	47	12
12	0.0808	2.05232	1.588	5.20864	41	9.3
13	0.072	1.8288	2.003	6.56984	35	7.4
14	0.0641	1.62814	2.525	8.282	32	5.9
15	0.0571	1.45034	3.184	10.44352	28	4.7
16	0.0508	1.29032	4.016	13.17248	22	3.7
17	0.0453	1.15062	5.064	16.60992	19	2.9
18	0.0403	1.02362	6.385	20.9428	16	2.3
19	0.0359	0.91186	8.051	26.40728	14	1.8
20	0.032	0.8128	10.15	33.292	11	1.5
21	0.0285	0.7239	12.8	41.984	9	1.2
22	0.0254	0.64516	16.14	52.9392	7	0.92
23	0.0226	0.57404	20.36	66.7808	4.7	0.729
24	0.0201	0.51054	25.67	84.1976	3.5	0.577
25	0.0179	0.45466	32.37	106.1736	2.7	0.457
26	0.0159	0.40386	40.81	133.8568	2.2	0.361
27	0.0142	0.36068	51.47	168.8216	1.7	0.288
28	0.0126	0.32004	64.9	212.872	1.4	0.226
29	0.0113	0.28702	81.83	268.4024	1.2	0.182
30	0.01	0.254	103.2	338.496	0.86	0.142
31	0.0089	0.22606	130.1	426.728	0.7	0.113
32	0.008	0.2032	164.1	538.248	0.53	0.091
Metric 2.0	0.00787	0.200	169.39	555.61	0.51	0.088
33	0.0071	0.18034	206.9	678.632	0.43	0.072
Metric 1.8	0.00709	0.180	207.5	680.55	0.43	0.072
34	0.0063	0.16002	260.9	855.752	0.33	0.056
Metric 1.6	0.0063	0.16002	260.9	855.752	0.33	0.056
35	0.0056	0.14224	329	1079.12	0.27	0.044
Metric 1.4	.00551	.140	339	1114	0.26	0.043
36	0.005	0.127	414.8	1360	0.21	0.035
Metric 1.25	.00492	0.125	428.2	1404	0.20	0.034
37	0.0045	0.1143	523.1	1715	0.17	0.0289
Metric 1.12	.00441	0.112	533.8	1750	0.163	0.0277
38	0.004	0.1016	659.6	2163	0.13	0.0228
Metric 1	.00394	0.1000	670.2	2198	0.126	0.0225
39	0.0035	0.0889	831.8	2728	0.11	0.0175
40	0.0031	0.07874	1049	3440	0.09	0.0137

Voltage Drop Calculator
by electrician.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.

Select Copper or AluminumCopperAluminum

Select American Wire Gauge (AWG) Size
18 AWG30 AWG28 AWG26 AWG24 AWG22 AWG20 AWG16 AWG14 AWG12 AWG10 AWG8 AWG6 AWG4 AWG3 AWG2 AWG1 AWG1/0 AWG2/0 AWG3/0 AWG4/0 AWG250 kcmil300 kcmil350 kcmil400 kcmil500 kcmil600 kcmil700 kcmil750 kcmil800 kcmil900 kcmil1000 kcmil1250 kcmil1500 kcmil1750 kcmil2000 kcmil

Select Voltage
120 Volts 1-phase240 Volts 1-phase208 Volts 3-phase 3-wire120/208 Volts 3-phase 4-wire277 Volts 1-phase480 Volts 3-phase277/480 3-phase 4-wire24 VDC or 1-phase AC48 VDC or 1-phase AC12 VDC or 1-phase AC6 VDC or 1-phase AC3 VDC or 1-phase AC

Enter 1-way circuit
length in feet

Enter Load
in amps

Voltage drop

Voltage at load end of circuit

Per Cent voltage drop

Wire cross section in circular mils

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