Updated
1/15/15
John Drake Services, Inc.
1427 E. 68th Street
Long Beach, CA 90805
electricity from the sun by John Drake II | home
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Wire loss - Voltage drop charts
Wire Loss Tables - 12 volt and 24 volt d.c.
Use these tables to determine the maximum distance one-way in feet of various gauges of
two-conductor copper wire from power source to load for a 2% drop in 12 volt and
24 volt system wiring.
You can go twice the distance where a 4% loss is acceptable.
Do not exceed the 2% drop for wire between PV modules and batteries.
A 4% to 5% loss is usually acceptable between batteries and lighting circuits in most cases.
Note that if you change an array from 12 volts to 24 volts and the wattage remains the same,
then the current is cut
in half. This allows you to go 2 times as far with the same wire gauge with the 24 volt array
as you could with the 12 volt array.
12 volt system - 2% voltage drop
Amps
|
14 ga.
|
12 ga.
|
10 ga.
|
8 ga.
|
6 ga.
|
4 ga.
|
2 ga.
|
1/0 ga.
|
2/0 ga.
|
4/0 ga.
|
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
|
15
|
22.5
|
35.5
|
57
|
90
|
145
|
180
|
290
|
10
|
4.5
|
7
|
12
|
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
|
3.6
|
5.5
|
9
|
14.5
|
23
|
29
|
46
|
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
|
24 volt system - 2% voltage drop
Amps
|
14 ga.
|
12 ga.
|
10 ga.
|
8 ga.
|
6 ga.
|
4 ga.
|
2 ga.
|
1/0 ga.
|
2/0 ga.
|
4/0 ga.
|
1
|
90
|
140
|
230
|
360
|
580
|
912
|
1440
|
|
|
|
2
|
45
|
70
|
115
|
180
|
290
|
456
|
720
|
1160
|
1440
|
2120
|
4
|
20
|
35
|
55
|
90
|
145
|
228
|
360
|
580
|
720
|
1160
|
6
|
15
|
24
|
35
|
60
|
95
|
150
|
240
|
386
|
486
|
760
|
8
|
11
|
17
|
30
|
45
|
71
|
114
|
180
|
290
|
360
|
580
|
10
|
9
|
14
|
24
|
36
|
57
|
91
|
145
|
230
|
290
|
460
|
15
|
6
|
9
|
14
|
24
|
38
|
60
|
96
|
153
|
192
|
300
|
20
|
4
|
7
|
11
|
18
|
29
|
45
|
72
|
115
|
145
|
232
|
25
|
3.6
|
5.6
|
9
|
14
|
23
|
36
|
58
|
92
|
116
|
184
|
30
|
3
|
4.8
|
7
|
12
|
19
|
30
|
48
|
77
|
97
|
154
|
40
|
|
|
5.6
|
9
|
14
|
23
|
36
|
58
|
72
|
112
|
50
|
|
|
4.6
|
7.2
|
11
|
18
|
29
|
46
|
58
|
92
|
100
|
|
|
|
|
5.8
|
9.2
|
14.4
|
23
|
29
|
46
|
150
|
|
|
|
|
|
|
9.6
|
15.4
|
19.4
|
30
|
200
|
|
|
|
|
|
|
7.2
|
11.6
|
14.6
|
22
|
Wire Loss Tables - 48 volt
Use these tables to determine the maximum distance one-way in feet of various gauges of two-conductor copper wire
from power source to load for a 2% drop in 48 volt and 120 volt system wiring.
You can go twice the distance where a 4% loss is acceptable. Do not exceed the 2% drop for wire between PV modules
and batteries. A 4% to 5% loss is usually acceptable between batteries and lighting circuits in most cases.
48 volt system - 2% voltage drop
Amps
|
14 ga.
|
12 ga.
|
10 ga.
|
8 ga.
|
6 ga.
|
4 ga.
|
2 ga.
|
1/0 ga.
|
2/0 ga.
|
4/0 ga.
|
1
|
180
|
280
|
460
|
720
|
1160
|
1824
|
2880
|
|
|
|
2
|
90
|
140
|
230
|
360
|
580
|
912
|
1440
|
2320
|
2880
|
4240
|
4
|
40
|
70
|
110
|
180
|
290
|
456
|
720
|
1160
|
1440
|
2320
|
6
|
30
|
48
|
70
|
120
|
190
|
300
|
480
|
772
|
972
|
1520
|
8
|
22
|
34
|
60
|
90
|
142
|
228
|
360
|
580
|
720
|
1160
|
10
|
18
|
28
|
48
|
72
|
114
|
182
|
290
|
460
|
580
|
920
|
15
|
12
|
18
|
28
|
48
|
76
|
120
|
192
|
306
|
384
|
600
|
20
|
8
|
14
|
22
|
36
|
58
|
90
|
144
|
230
|
290
|
464
|
25
|
7.2
|
11.2
|
18
|
28
|
46
|
72
|
116
|
184
|
232
|
368
|
30
|
6
|
9.6
|
14
|
24
|
38
|
60
|
96
|
154
|
194
|
308
|
40
|
|
|
11.2
|
18
|
28
|
46
|
72
|
116
|
144
|
224
|
50
|
|
|
9.2
|
14.4
|
22
|
36
|
58
|
92
|
116
|
184
|
100
|
|
|
|
|
11.6
|
18.4
|
28.8
|
46
|
58
|
92
|
150
|
|
|
|
|
|
|
19.2
|
30.8
|
38.8
|
60
|
200
|
|
|
|
|
|
|
14.4
|
23.2
|
29.2
|
44
|