Fusing question (short circuit)

[UnderLoK]

How many amps are displaced if one of my lines was to short out? Obviously I don't understand what happens during a short circuit so it leads me to the following...

I ask this seemly simple question because I have 4 1/0 power runs from the front bus (1 D3400 and 2 270a alts) to the back which are fused to 300a each (below wire rating) in the front of the truck. They then in turn will go to a positive bus in the rear which will then be fused to another positive bus that carries the other batteries (2 D3400) and amplifiers (the 1/0 runs to the amps are individually fused at 300a as this is max draw for each amp). In this bus to bus connection what should it be fused to and is doing it this way still safe?

The only reason I'm thinking of doing this bus to bus fusing is because of space. Space in my truck is a constant issue and bus to bus fusing fits as to where 4 1/0 blocks do not.

I guess what this whole thing boils down to is my lack of understanding as far as how many amps could be displaced in my application if the line shorts out (100? 500? 3000?) and if it's instantaneous or if it builds over time. Knowing that would obviously give me a better understanding of the danger (if any) involved in fusing this way.

Thanks guys!

Edited August 16, 2010 by UnderLoK

[UnderLoK]

Bumpage...

[Guest]

for a short circuit that is + directly to ground, dont quote me on this, but i heard its around a few hundred to a few thousand amps.

[HHR Ed]

amps are drawn, not displaced.

And the amount of amps drawn depends on your batteries and wire.

Most likely it will be the maximum amperage that your wire can carry if your batts can supply more than the wire can carry.

If your wire can carry more than what your batteries can supply, then the full current capacity will be unloaded from the batteries.

This will be many thousands of amps of current in your case.

[HHR Ed]

haha, nice avatar Kranny

[Guest]

haha, nice avatar Kranny

thanks haha beachjoshua helped me on that one.

[UnderLoK]

amps are drawn, not displaced.

And the amount of amps drawn depends on your batteries and wire.

Most likely it will be the maximum amperage that your wire can carry if your batts can supply more than the wire can carry.

If your wire can carry more than what your batteries can supply, then the full current capacity will be unloaded from the batteries.

This will be many thousands of amps of current in your case.

Thanks guys!

So to play devils advocate that would mean that if I fuse bus to bus at let's say 1200a and a wire shorts out (grounds out) they will pop no matter what (the D34's can do like 3000a) or should I be fusing at my max draw of 600a across the bus?

Just to reiterate, I'm just looking to fuse my wires in the back of the truck using as little space as possible and this seemed like the best option.

Edited August 17, 2010 by UnderLoK

[skittlesRgood]

i vote, ditch the bus bar fuse. just run unfused wire between the batteries in the back and dont get them mixed up.

[skittlesRgood]

Thanks guys!

So to play devils advocate that would mean that if I fuse bus to bus at let's say 1200a and a wire shorts out (grounds out) they will pop no matter what or should I be fusing at my max draw of 600a across the bus?

Just to reiterate, I'm just looking to fuse my wires in the back of the truck using as little space as possible and this seemed like the best option.

if one wire shorts out and it runs to a 1200amp fuse, the wire will burn up way before those fuses pop. you wire burns at 350-400amps? so the fuses wont do any good here.

[HHR Ed]

Thanks guys!

So to play devils advocate that would mean that if I fuse bus to bus at let's say 1200a and a wire shorts out (grounds out) they will pop no matter what (the D34's can do like 3000a) or should I be fusing at my max draw of 600a across the bus?

Just to reiterate, I'm just looking to fuse my wires in the back of the truck using as little space as possible and this seemed like the best option.

You want to fuse on each wire, and fuse lower than what the wire can carry. The ampacity of the wire depends on its gauge, length, and material. So gather the data on your particular wire, then research how much current each wire can carry at your batteries voltage. And fuse below that rating.

Or do what I do and dont use fuses at all. I drive around with 0awg cutters just incase.