Power Wire Grounding out after fuse

[metalheadjoe]

So it is some sort of fancy one way fuse then? If the fuse blows to stop power from exiting a device, wouldn't blowing said fuse also stop power from entering the device?

The fuse blows because there is excessive current going through it. The current rush is between the battery and the short to ground, because ground is the opposite polarity. When a direct short to ground occurs, there is higher current between the supply positive and negative. In the context of your question, "entering the device" means going to ground. Electrons move between positive and negative. A short causes a direct path between the two, meaning less resistance, and therefore higher current, which results in a blown fuse.

 

[metalheadjoe]

So it is some sort of fancy one way fuse then? If the fuse blows to stop power from exiting a device, wouldn't blowing said fuse also stop power from entering the device?

I'm not going to get into the conventional vs. electron flow argument, if that's what you're alluding to. I can't tell if you're arguing to argue or genuinely confused. I'm willing to explain things as much as I can, but not if you want to make snide remarks such as "fancy one way fuse".

Think I'm wrong? Test it. Do some research. Do some experiments. By all means, please record it on video. If you correctly connect a brand new amp to positive and negative of a battery, short the positive to negative in between the power supply and the amp, and the amp is damaged because of the short, I'll buy that damaged amp from you for whatever you paid for it. I'm putting my money where my mouth is. Or how about I buy a brand new amp and run the same experiment: if the amp isn't damaged you pay me what I bought it for. We can put something in writing before we go through with either method. This would be the best way to put the issue to rest.

 

[metalheadjoe]

Think of it like traffic heading through a stoplight. The stoplight lets a limited amount of traffic through. Then, a detour opens up that lets an unlimited amount of vehicles through to the same destination. The traffic between the stoplight and the detour come from the same place, but traffic through the detour doesn't affect traffic through the stoplight.

 

[Squirrel!]

So it is some sort of fancy one way fuse then? If the fuse blows to stop power from exiting a device, wouldn't blowing said fuse also stop power from entering the device?

A fuse is to stop power from ENTERING a device, NOT "exiting a device". A fuse is to protect both the equipment as well as the power source from damage or fire. Nothing more. The same as your breakers in your house electric panel. There are no "exit fuses". There are no "1 way fuses".

 

[JulesH]

If there is a short inside the amp then there is a fault in the amp. The internal fuse is simply reacting to a short already inside the amp ripping its way through the fets and destroying them.
Essentially, saying that the amp's fuse protects the amp from damage is like saying a car's airbag prevents an accident.