Outer Limits 4x4 Board

hey guys i have the rule book on 240V cable selection now going on amperage and cable it is a bit big then really needed so im wondering if there is a formula to change the 240 down to 12 or there is somewhere i can download a rule book or something

Bartso wrote:hey guys i have the rule book on 240V cable selection now going on amperage and cable it is a bit big then really needed so im wondering if there is a formula to change the 240 down to 12 or there is somewhere i can download a rule book or something

Well if you have to cable selection refering on amperage you can convert it to 12V use.
Use power=voltage*current
Power is in watts;

So u should have an estimate what sort of wattage ur drawing then

current=power(watts)/voltage(12v)

Hope thats wat ur after
Cheers Dan

Hi Bartso, this is a bit of a long rant, but cable rating is based on the amount of current a cable can handle before the cable heats the insulation, so whether the cable is 1 meter long or 100 meters long, the current rating is the same.

What is NOT the same and the main consideration, is the voltage drop that will occur over a given distance and the longer the distance the greater the voltage drop.

There are some formulas that can be used to correctly determine the minimum size of cable needed for a given current requirement over a given distance and what a load of crap, BUT as long as you use a cable bigger than the current requirements needed then you shouldn’t get too much of a voltage drop.

You haven’t stated what you intend to use the cable for but to throw another spanner in the works. AC cable is not really suitable for automotive use for a couple of reasons. I think you will find AC cable insulation has a low ignition temperature rating so it’s not as safe as automotive wire and the size of the strands used in AC cable is thicker than those used in automotive cable so the AC cable is very susceptible to fatigue and breaking.

Go with automotive cable and save a lot of time and effort.

Cheers.

Bartso wrote:hey guys i have the rule book on 240V cable selection now going on amperage and cable it is a bit big then really needed so im wondering if there is a formula to change the 240 down to 12 or there is somewhere i can download a rule book or something

You can subscribe to Australian Standards and download different books but nothing is free. AS3008.1.1 is the standard i assume you have in front of you. There is 4 tables for each situation and the last two will be the most relevant in this situation. They cover your V105 and V110 cables.

Is this for your battery going on the rear of the truck? Just run some big arse offcuts.

if you know what you want to do lets us know and we can get the cable rating info for you and do the maths and let you know what the voltage drop etc will be over certain cables and you can make your decision on what you need.

Simon

well a couple of things im moving my 12v bat to the rear this isn't a prob got some off cuts at work today 150mm so that is going to run from the + bat to the starter then 150mm off the engine on to the chassis then from the neg side of the bat to the chassis then im running a wire from my starter to the alt i will be using 16mm for this??

also i have a 24v alt which has an output of roughly 60 amps (i think) its a nissan safari 24v alt will 16mm be big enough to run from the 24v bat which is in the rear to the alt up front??

all these cables are multi strandard flexible stuff

150mm is heaps as a starter cable.

The 16mm is rated at about 140Amps so will be heaps for the 24v alt.

Simon.