Wire Sizing Charts

Here is a few charts to help you with what size of wire you need.  

This information is provided as a reference only. 

Wire Sizing Chart 12 Volt SystemMaximum one-way distance ( feet ) for 2% voltage loss in 12 volt systems. Wire Size (AWG)Do not exceed the 2% drop for wire between PV modules and batteries.

Amps	14	12	10	8	6	4	2	1/0	2/0	4/0
1	45	70	115	180	290	456	720	.	.	.
2	22.5	35	57.5	90	145	228	360	580	720	1060
4	10	17.5	27.5	45	72.5	114	180	290	360	580
6	7.5	12	17.5	30	47.5	75	120	193	243	380
8	5.5	8.5	11.5	22.5	35.5	57	90	145	180	290
10	4.5	7	11.5	18	28.5	45.5	72.5	115	145	230
15	3	4.5	7	12	19	30	48	76.5	96	150
20	2	3.5	5.5	9	14.5	22.5	36	57.5	72.5	116
25	1.8	2.8	4.5	7	11.5	18	29	46	58	92
30	1.5	2.4	3.5	6	9.5	15	24	38.5	48.5	77
40	-	-	2.8	4.5	7	11.5	18	29	36	56
50	-	-	2.3	3.6	5.5	9	14.5	23	29	46
100	-	-	-	-	2.9	4.6	7.2	11.5	14.5	23
150	-	-	-	-	-	-	4.8	7.7	9.7	15
200	-	-	-	-	-	-	3.6	5.8	7.3	11

 

Wire Sizing Chart 12 Volt SystemMaximum one-way distance ( feet ) for 5% voltage loss in 12 volt systems. Wire Size (AWG) A 5% loss is acceptable between batteries and lighting circuits in most cases.

Amps	14	12	10	7	6	4	2	1	1/0	2/0	4/0
1	106	169	269	427	679	1080	1717	2166	2730	3444	5475
2	53	85	134	214	340	540	859	1083	1365	1722	2738
4	27	42	67	107	170	270	429	542	682	861	1369
6	18	28	45	71	113	180	286	361	455	574	913
8	13	21	34	53	85	135	215	271	341	430	684
10	11	17	27	43	68	108	172	217	273	344	548
15	7	11	18	28	45	72	114	144	182	230	365
20	-	8	13	21	34	54	86	108	136	172	274
25	-	-	11	17	27	43	69	87	109	138	219
30	-	-	9	14	23	36	57	72	91	115	183
35	-	-	-	12	19	31	49	62	78	98	156
40	-	-	-	-	17	27	43	54	68	86	137
45	-	-	-	-	15	24	38	48	61	77	122
50	-	-	-	-	14	22	34	43	55	69	110

 

Wire Sizing Chart 24 Volt SystemMaximum one-way distance ( feet ) for 5% voltage loss in 24 volt systems. Wire Size (AWG)A 5% loss is acceptable between batteries and lighting circuits in most cases.

Amps	14	12	10	7	6	4	2	1	1/0	2/0	4/0
1	213	338	537	854	1359	2160	3434	4332	5460	6887	10951
2	106	169	269	427	679	1080	1717	2166	2730	3444	5475
4	53	85	134	214	340	540	859	1083	1365	1722	2738
6	35	56	90	142	226	360	572	722	910	1148	1825
8	27	42	67	107	170	270	429	542	682	861	1369
10	21	34	54	85	136	216	343	433	546	689	1095
15	14	23	36	57	91	144	229	289	364	459	730
20	-	17	27	43	68	108	172	217	273	344	548
25	-	-	21	34	54	86	137	173	218	275	438
30	-	-	18	28	45	72	114	144	182	230	365
35	-	-	-	24	39	62	98	124	156	197	313
40	-	-	-	-	34	54	86	108	136	172	274
45	-	-	-	-	30	48	76	96	121	153	243
50	-	-	-	-	27	43	69	87	109	138	219

 

Maximum Ampacity for Copper and Aluminum Wire Wire Size Copper Aluminum 14 25 . 12 30 25 10 40 35 8 55 45 6 75 60 4 95 75 2 130 100 1 150 115 1/0 170 135 2/0 265 150 4/0 360 205

 

NEC allows rounding up cable ampacity to next standard fuse or breaker.