My amp has a 40 amp fuse plugged in. The wiring kit that i got came with 80 amp. I went to my local car audio store and got a 30 amp for my inline fuse. What is the leeway for amperage from one fuse to another? I heard it should be the same, everywhere i went though did not have a 40 amp fuse for the inline.
if the amp has a 40A fuse, that means it's capable of drawing up to 40A. You'll want an in-line fuse rated for 40A or slightly larger. The in-line fuse is mainly to prevent a dead short so as long as teh amp itself is fused, you'd be pretty safe going with a slightly larger in-line rating.
so using a fuse that is smaller than the one on the amp for the inline isnt recommended? could it cause any harm to my vehicle? Could i use a 80 amp fuse for the inline with the 40 amp on the amplifier?
Read the thread. You need to have a 'slightly' larger fuse for the in-line. Having a smaller in-line fuse would just blow it when the amp is pulling hard. It won't hurt the car. Having a too large inline amp is not too bad but you better hope the amp's fuse is working...
if the fuse is 30A it may work fine unless you use the amplifier at full output. then all that will happen is you'll blow the fuse. just means you'll need to replace that 30A fuse. the 80A fuse is twice the size you need. I think you should look elsewhere for a 40A or 50A fuse for that holder. try partsexpress.com or sounddomain.com they both sell a huge assortment of fuses for car audio applications.