I currently have a 4 channel amp powering my speakers in my car. I am planning on getting a 12" sub and an amp to power it. I have 4 gauge wire run all the way to the trunk for my current amp. I am going to get a distribution block and run the 4 gauge wire to the block and 8 gauge wire from the block to each amp. My question is how do I go about determining what size fuse to use. I already have a 60amp fuse for the current amp and Im not sure what size fuse I will need to replace it with. The new amp will most likely need a 60amp fuse as well so do I run a 120 amp fuse or keep my 60 amp fuse. Im pretty sure I just need to run a single 60 amp fuse but I want to make sure before I start buying stuff. Thanks.

 

theres a way to determin this. its watts/volts= amp so i dont know what you are running wattage wise. but heres a example! i have a 2k watt amp at 14 volts so 2000/14= 142.8 i usually go the next size up. or whatever the company suggests. thats how i was told to do it

 

Well let me rephrase. I know I need a 60amp fuse for amplifier #1 and Im 99% sure I will need a 60amp fuse for amplifier #2. My main question is, since both amps will be getting power from a single source (4 gauge wire from battery) and both amps will be sharing a single fuse, do I need a 120amp fuse or a 60amp fuse? Or do I need no fuse on the 4 gauge and a 60amp fuse on each 8 gauge wire after the distribution block?

 

yes thats what i would do. just up the fuse on the 4 gauge wire. i used to have 3 amps on a distribution block and only fused the main wire going into the distribution block. i had zero problems.

 

Ah good thing I asked then. I would have just left it at 60amps. Now I dont see a 120 amp fuse available but there is a 100amp and a 125amp. Should I use a 125amp and not worry about the extra 5 amps or should I play it safe and go with a 100amp fuse?

 

fuse 16 inches from termination of wire, and 16 inches from begining is code.

if yoru power draw is 60 amps x2 obviously you'll blow a 60 amp fuse on your power run.

 

What 'code' is that? Can you provide a reference?

BBEngineer

 

My fuse is probably a foot maybe less from the battery.

 

I believe the most important baseline is the gauge/size of cable used.

Thus the breaker(s)/fuse(s) can be sized as high as the ampacity of the wire, as long as the amp(s) are protected with their own breaker(s) or fuse(s).

And NOT all same gauge wire has/have the same ampacity ... check with manufactures' specs.

Also, there is nothing wrong with going undersized protection for the wire ... it's safer that way.

And just because an amp may be showing 2 (two) 20 amp fuses sticking out its side(s), it is not necessarily protected to/at 40 amps. It could be split internally, supplying 2 (two) paths; 20 here, & 20 there.

I prefer breakers.

 

You can use ONE fuse, or breaker, & run 2 (two) amps on it with ZERO problems.