Have you thought of this when you externally fused your top$$ amp!!

[MarioB]

600a is alot of current for an amp to pull. although We did purple a 500a fuse in my car

[SnowDrifter]

I'm going to answer your question with a couple scenarios:

You have a high end amp, with dual inputs. A 5k, with a 200a fuse on each wire.

Scenario 1:

All is good, playing music as normal. Suddenly: One of the wires shorts out against something. You hear some sparking coming from the back, smell a burnt smell, then hear two loud "pops" as each of the fuses blow - and not a moment too soon. Now you are wondering... Only one wire shorted out, but why did both fuses blow? The answer is this: Internally on the amp, all of your inputs are paralleled together. So even if one fuse blows, power will still be traveling across the other wire, into the amp, through the buss bar, out through the other input, and to the short. Then the other fuse blows. If you didn't fuse these wires, you'd have an uncontrolled over-current situation - a short.

Scenario 2: You are wired blow rated. One of those limit pushers, trying to get the most power out of your equipment, but still smart enough to fuse. You are hammering on your favorite song, it's almost over, you are going full tilt with no intentions of turning it down. Then your amp cuts out and you see both fuses blown. No shorts anywhere in the wire. What happened here? If you are pulling say.... 600 amps with your 400amps of fusing, you will eventually push a fuse to the point of failure (as it's designed). When one fuse blows, all the current will be going through the other wire/fuse. It's already hot right now and on the edge of blowing. Those 600 amps going through a single fuse, already on the edge will pop it pretty quickly.

Scenario 3: You are driving down the highway, when your music cuts off, your subs make a loud buzzing noise. You pull off, turn the car off, and run to the back to investigate. Even with the car off, your subs are making that awful noise. Once you open the trunk, you can barely see, your amp is pouring smoke out of every pore, you hear crackling on the inside and see glowing as some of the internal parts become red hot. Then: "Pop! Pop!" your fuses blow, the smoke subsides, and your subs stop buzzing. Good thing you fused, that amp was hard to get to - you aren't sure you could have ripped the wires out before your car went up in flames.

[Johnp71]

I'm going to answer your question with a couple scenarios:

You have a high end amp, with dual inputs. A 5k, with a 200a fuse on each wire.

Scenario 1:

All is good, playing music as normal. Suddenly: One of the wires shorts out against something. You hear some sparking coming from the back, smell a burnt smell, then hear two loud "pops" as each of the fuses blow - and not a moment too soon. Now you are wondering... Only one wire shorted out, but why did both fuses blow? The answer is this: Internally on the amp, all of your inputs are paralleled together. So even if one fuse blows, power will still be traveling across the other wire, into the amp, through the buss bar, out through the other input, and to the short. Then the other fuse blows. If you didn't fuse these wires, you'd have an uncontrolled over-current situation - a short.

Scenario 2: You are wired blow rated. One of those limit pushers, trying to get the most power out of your equipment, but still smart enough to fuse. You are hammering on your favorite song, it's almost over, you are going full tilt with no intentions of turning it down. Then your amp cuts out and you see both fuses blown. No shorts anywhere in the wire. What happened here? If you are pulling say.... 600 amps with your 400amps of fusing, you will eventually push a fuse to the point of failure (as it's designed). When one fuse blows, all the current will be going through the other wire/fuse. It's already hot right now and on the edge of blowing. Those 600 amps going through a single fuse, already on the edge will pop it pretty quickly.

Scenario 3: You are driving down the highway, when your music cuts off, your subs make a loud buzzing noise. You pull off, turn the car off, and run to the back to investigate. Even with the car off, your subs are making that awful noise. Once you open the trunk, you can barely see, your amp is pouring smoke out of every pore, you hear crackling on the inside and see glowing as some of the internal parts become red hot. Then: "Pop! Pop!" your fuses blow, the smoke subsides, and your subs stop buzzing. Good thing you fused, that amp was hard to get to - you aren't sure you could have ripped the wires out before your car went up in flames.

That third scenario is so terrifying I'd do anything to avoid this chaos from happening. On my end, my only option is to fuse them. I always watch my volume, never went full tilt.

Her guts:

[Colin - STAPUFT]

Nailed it Snow.