12 Volt Technical Articles, Wiring Diagrams

What is the correct size cable for my 12 volt system

Posted on by JTS 12volt

CABLE LENGTH AND CURRENT CAPACITY GUIDE

SHOWING CABLE SIZE IN mm²

This page shows the comparisons between the Amperage of your circuit and the gauge of the wire require to carry the current. You may ask “what size wiring should I use?”, use this chart to determine the safest, most efficient wiring thickness, you should use for your next 12 volt system, we are also able 12 volt shop.

AMPS 

C
A
B
L
E

L
E
N
G
T
H

I
N
M
E
T
R
E
S
12
16
20
25
32
50
63
80
105
125
155
1
1
1.5
2.5
4
6
10
16
25
35
50
70
2
2.5
2.5
4
4
6
10
16
25
35
50
70
3
4
4
6
6
10
16
16
25
35
50
70
4
4
6
6
10
10
16
25
25
35
50
70
5
6
6
10
10
16
25
25
35
50
50
70
6
6
10
10
16
16
25
25
35
50
70
70
7
10
10
16
16
16
25
35
50
70
70
Over
8
10
10
16
16
25
35
50
50
70
Over
9
10
16
16
25
25
35
50
70
Over
10
10
16
16
25
25
50
50
70
11
10
16
16
25
25
50
70
70
12
16
16
25
25
25
50
70
Over
13
16
16
25
25
35
50
70
14
16
16
25
25
35
70
70
15
16
25
25
25
35
70
Over
16
16
25
25
35
50
70
17
16
25
25
35
50
70
8 B&S=
8mm²
18
16
25
25
35
50
70
6 B&S=
13.5mm²
19
25
25
25
35
50
Over
4 B&S=
20mm²
20
25
25
35
50
50
3 B&S=
25mm²
30
35
35
50
70
Over
40
35
50
70
Over
50
70
70
Over
60
70
over
70
Over

 

Example. A Duoetto 12 volt 10 litre water heater draws 22 amps on 12 volt and is 4 metres from the battery. It therefore requires a cable of at least 8mm² or 8 B&S.

Note: Cable capacity at 12.6 volt to a maximum loss of 5%.