Match the fuse with the fuse on the amplifier. 40 sounds about right for that much wattage. but if the amp can draw more power then you fuse the wire for the fuse will blow. The fuse on the wire is to protect the wire, it ensures the wire will not exceed its capability to handle current.
how do you know the power wire is 4 guage, it could be 8 guage. And there is no need to fuse the power wire with a fuse larger then the one on the amp any ways. If you have multiple runs of power wire, you fuse the line for the max ampere you want it to draw(because melting a power wire and having it ground off to the nearest piece of frame would suck)
how do you know the power wire is 4 guage, it could be 8 guage. And there is no need to fuse the power wire with a fuse larger then the one on the amp any ways. If you have multiple runs of power wire, you fuse the line for the max ampere you want it to draw(because melting a power wire and having it ground off to the nearest piece of frame would suck)