300amp fuse with 0 gauge wire?

[n2audio 5,000+ posts]

That's why I've never been concerned with installing another fuse at my distro block for my 4g to amp from 0g because it's length is under 2 feet and it could easily handle the amperage the 0g can provide from ~15 feet.
You'll see this concept in every day use. It's why your speaker VCs can have such a small wire. It's why your fuse holder can pass 300amps on a very thin piece of solid metal. Length has everything to do with how much a conductor can handle.

Not exactly convincing examples.

Speaker VC's higher voltage - less current.

Fuses - the issue there is melting copper, which happens at nearly 2000 degrees.

With wire we're concerned about the insulation which melts as low as 175 if it's PVC.

 

[jrwalte 10+ year member]

Not exactly convincing examples.Speaker VC's higher voltage - less current.

Yes. And the 14g to 10g you use to run the power from your amp to your VC is at the same voltage, yet at your VC with a couple inches of wire you have 18g or 20g capable of carrying the same as the longer run. Seems like a perfect example to me.

 

[knukonceptz 10+ year member]

Got to run, so just a quick thought - time - how long will it take to heat up that 3' of 4 gauge cable to melting point? Three time faster then the 1/0 (according to your numbers), but if it takes 200 STRAIGHT hours to heat up 3' of 4 gauge at a CONSTANT 300A to melting point, you'd have 600 hours on the 1/0?

Music is not constant - DB Drag is a burp. While 200 hours is a guess - the forumla is surely out there

I understand that area will play a role in thermal capacity, but the resitance of the material takes a larger role in our applications as the power is not a constant demand

 

[n2audio 5,000+ posts]

Yes. And the 14g to 10g you use to run the power from your amp to your VC is at the same voltage, yet at your VC with a couple inches of wire you have 18g or 20g capable of carrying the same as the longer run. Seems like a perfect example to me.

That's just an argument for overkill on speaker wire size.
At 10' 14 ga is good for close to 800w at 4 ohms. If a person actually NEEDS 10 ga speaker wire the tensile leads aren't going to be 18 or 20 ga.

 

[SethPhillips 5,000+ posts]

im running 10ga to my sub's.. //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[Low_e_Red 10+ year member]

The fuse is there as a safety and to protect YOU in case of accident. As a result you have two options:
1) Fuse based on the max capacity of the wire.

2) Fuse based on system draw

#1 is fine for the main inline fuse, but in a dist block is down right silly. Most blocks use 4 gauge out, a 4 gauge wire that is 3' long can handle over 300A so fuse selection in a block based on gauge is not practical. It does not make the system better to use a 150A fuse on a 30A draw.

#2 from a safety stand point is more logical - Even if your amp lists three 30A fuses (90A) the ONLY time it will draw that is during a bass note/sweep. No normal music CD will create that kind of load, the beats too quick. Grab a clamp meter, you'll see what I mean.

 

What we recommend is to add up the system's total draw for the main fuse and then fuse each leg of a block according to the load on that leg. Reason for this method - safety! If you have 0 gauge running and a 300A fuse under the hood and 90A worth of draw, there is ZERO gain by putting a single 300A fuse in place of a 100A fuse. Under normal use, it makes no difference, but what happens in an accident? Why risk it if you have no need for it?

 

I am sure this is why MOST companies will tell you to fuse for the draw - safety. Just because your speedo says 160mph does not mean your car will go that fast

AMEN BROTHA!