Electrics help

[Rizzo16]

Hi,
I'm new to this forum and was looking for some advice on getting the electrics sorted out in my van conversion (I have absolutely no experience with this)
So far I've hooked up my 12v leisure battery and put in a split charge relay using a kit from ebay.
I've got a cool box and a usb port that I wanted to hook up to my fuse box but am struggling with working out what size cables to be using. The amps for the different things I'll be connecting up will be low ranging from a couple of amps to around 8 amps. Looking online though has made the wire size quite confusing as it seems to suggest that the size wire will depend on the length that the cable will be running. Any advice on how to calculate this or what will be easiest would be great as I obviously don't want to get this wrong and set up something that won't be safe.
Thanks

 

[pappajohn]

If you go to this website it will calculate the correct size cable.
At the first box enter 3% as an acceptable loss.

Click HERE

 

[tonyidle]

If you look at cable size vs current (Amps) that it can carry safely then a particular cable specified to carry a particular current will do so safely over any length you choose.

However wires do have resistance and as length increases so do losses. This can mean that whatever is on the end of the cable receives a lower voltage than intended. Something that can be overcome by increasing the size of the cable.

 

[Rizzo16]

Thanks very much for the replies, very helpful.