CABLING & WIRING ON 4X4 VEHICLE INSTALLATIONS
Installations of sophisticated equipment into 4x4 vehicles are often ruined by poor or inadequate wiring.
It is evident that in order to optimse the current flowing from one source to another, or several others in the case of multiple batteries, it is vital that losses are minimised and that wiring is of the thickness and specification to aloow the optimal transfer of generated power with imimal losses.
To this end there is an industry norm on this subject which holds good for all 4x4 installations, as well for emergency vehicles. The table below will give you an indication of cable thickness required in relation to power transmitted.
| AMPERAGE |
THICKNESS |
| 20 |
6mm |
| 40 |
16mm |
| 80 |
25mm |
| Above 80 |
35mm |
In addition to the ability of the wiring to transfer the voltage to the source, there is of course a factor of losses which relate directly to distance, ergo: length of wiring over which the voltage is being transfered. The table below wil give you an indication of the degree of losses that you can expect employing the different thickness of cabling used in the average 4x4 application.
| CABLE THICKESS (X) |
V loss at 10A |
V loss at 20A |
V loss at 40A |
| 4mm |
0.38 V/m |
0.10 V/m |
0.19 V/m |
| 6mm |
0.26 V/m |
0.06 V/m |
0.13 V/m |
| 10mm |
0.15 V/m |
0.04 V/m |
0.08 V/m |
| 16mm |
0,10 V/m |
0.02 V/m |
0.05 V/m |
| 25mm |
0.06 V/m |
0.02 V/m |
0.03 V/m |
| 35mm |
0.04 V/m |
0.01 V/m |
0.02 V/m |
The voltage loss per meter by the distance of the loom length. Thus employing 16mm cable, transfering 40A, over 10M would equate to a loss of 1 Volt.
One should also remember that a loom has both positive and negative cables and thus you should double the cable length for these calculations. Losses will also be incurred with connectors and junctions, as well as fuses.
The over-riding principle is that it is better to have too much thickness, then too little.
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