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 SELECTION TABLE

Circuit Amperes

Circuit Watts

Wire gauge (for length in feet)

6V

12V

6V

12V

3'

5'

7'

10'

15'

20'

25'

0 to 2.5

0 to 5

15

30

18

18

18

18

18

18

18

3.0

6

18

36

18

18

18

18

18

18

16

3.5

7

21

42

18

18

18

18

18

18

16

4.0

8

24

48

18

18

18

18

18

16

16

5.0

10

30

60

18

18

18

18

16

16

16

5.5

11

33

66

18

18

18

18

16

16

14

6.0

12

36

72

18

18

18

18

16

16

14

7.5

15

45

90

18

18

18

18

14

14

12

9.0

18

54

108

18

18

16

16

14

14

12

10

20

60

120

18

18

16

16

14

12

10

11

22

66

132

18

18

16

16

12

12

10

12

24

72

144

18

18

16

16

12

12

10

15

30

90

180

18

16

16

14

10

10

10

20

40

120

240

18

16

14

12

10

10

8

25

50

150

300

16

14

12

12

10

10

8

50

100

300

600

12

12

10

10

6

6

4

75

150

450

900

10

10

8

8

4

4

2

100

200

600

1200

10

8

8

6

4

4

2