Cable rating

[Teeaitch]

I'm planning on fitting a 140amp VSR split charger. As usual, I'm confused about what rating cable and fuse I should use. Can anybody put me in the picture please, and while we're at it maybe someone can put me in the picture about how to calculate for this kind of issue. Thanks.

[Funkychops]

Fuse should be rated lower than the cable (so that the fuse goes first)

I think a general rule of thumb is 1.25x normal current for the fuse rating (http://www.judgeelectrical.co.uk/domest ... ating.html). Using P=IV you should be able to work out the current draw for the appliance.

Then make sure the cable rating is higher than the fuse. Your safety margin depends on various factors like environment, number of cables in the run etc but all this is doing is making sure the wire doesn't get too hot to cause a fire. You can't really go too high - all higher does is give you a thicker and less manageable cable.

For VSR connections to battery and earth, you need to go big in terms of cable rating. Should be able to find out the exact charge current going into the battery but I would imagine it's high

[Teeaitch]

Thanks for that.

[Mocki]

There is no point using cable that’s rated more than the out put of the alternator, it’s never going to exceed what the alternator can produce . 
16mm2