Automotive Cable Sizing

[Anguz]

my kit car loom was made on nightshift, its all black 105'c laptherm, which is what we used where i worked at the time.. has critchley markers on the ends, most of which are still readable 20 years on

 

[MetalMonkey]

See #7
I've fitted a fan controller with temperature controls. It's designed for modern cars with twin fans, aircon over-ride, ignition off over-run, fused, relayed etc etc. Its prewired parts are in 2mm2. My fan is actually nominally 150W = 12.5amps.

You can still use the outputs of the fan controller to switch an additional relay.
Not knowing what sort of fan controller it is, or a circuit layout etc it is hard to give a definitive solution, but that is certainly still an option.

12vplanet have a handy volt drop calculator, obviously based on their cable, but should put you in a the ballpark.
https://www.12voltplanet.co.uk/voltage-drop-calculator.html

Assuming the 3m of cable length includes both the feed and return (1.5m each way), 2.00mm csa is going to give 0.35V drop which is meh. On 1.0 it will be 0.7V which isn't great.
2.0 would be the better choice, but if it was me I would beef it up.

 

[Matrixx]

Out of interest, what is 'tri-rated' and how does it differ from the cable I linked to on the AES site?

It is multi stranded and flexible, and as mentioned heat resistant etc, we used it in control panels and also on engine wiring looms. you can get high current cable that has the copper coated/tinned to allow higher currents for the same CSA.

 

[m_c]

Tri-rated isn't really meant for automotive applications, but it will work.

The main reason you won't see it mentioned much by the automotive suppliers, is modern 'high performance' automotive wiring uses a thinner insulation, which allows for smaller wiring looms. For a few wires, it's not really much benefit, but when you have looms with 20+ wires, it makes a noticeable difference.
Plus in the case of an overload, the insulation on high performance wire will melt into the wire, unlike older automotive wiring where the insulation would melt and fall off.