Fuse size based on wire gauge or the amplifier's fuse rating?

[ryanwiggum]

Some people to fuse (near the battery) based on wire size and others say the fuse size depends on the fuse rating on the amp. Which is the right way?
I'll be using a 4 gauge wire from the amp to the battery. The fuse rating on the amp is 90

so either its:
-a 125 amp fuse (or a size smaller)
-a 90 amp fuse

[btnhfan]

Fuse by wire size. Thats why amps have their own fuses.

[pks71]

If your amplifier has internal fuses, fuse by wire size ...
If your amplifier doesn't have internal fuses, use the recommended inline fuse size ...

If you are running multiple amplifiers, the inline fuse at the battery should be fused by the wire size and the fuses at the distribution block should be based on the amlifiers ...

X2!