What will happen if? (Fuse)

[npcout]

I have a 4 channel amp installed with 8 gauge power wire with a 60 amp inline fuse up by the battery. (amp has 2 25amp fuses on it) and i also just installed a 2nd amp for my subs with 4 guage power wire, which has 4 25 amp fuses on it. Right now, i just have a 60 amp fuse up by the battery but I ordered a 100 amp circuit breaker yesterday, but im finishing the install tommorow, (setting gains etc) and i wont get the circuit breaker til saturday or maybe monday.

What would happen if i played my system without the 100 amp circuit breaker for a day or two, with the 60 amp fuse for my sub amp instead of the 100?

Thanks a lot guys. I dont wana ruin my cars electrical system.

[GlassWolf]

as long as you don't draw more current than the fuse can take, you're fine.
otherwise, you blow the fuse. that's all.

[geolemon]

Remember, each of your fuses has a job.
The job of the fuses that are built into your amps is to protect the amplifier.
The job of the fuse that is underhood has nothing to do with how much current the amplifier is going to draw - it's job is to protect the wire, in the event that a short-circuit developed somehow... like a screw getting put through the wire, the insulation of the wire getting worn away, etc.
In that event, the fuse up front is going to pop.
It's not supposed to have anything to do with your amplifiers or how much current they are drawing...
If it's popping under normal use, it's too small, it's that simple.

(of course, if it's popping under normal use, you may be running the wrong gauge wire - there's nothing wrong with going "too big" on your power wire, but "too small" can be dangerous!)

You want your fuse up front to be at least as large as the total fusing in your trunk... all the amps, processors, and whatever that are back there... and you might add 10% to be safe, because there are going to be some losses in the wire to account for.

If your amps total up to more than 80a, I'd make sure I was running something larger than 4 gauge wire.

Even 1/0 gauge is cheap these days... you can get a whole kit that includes everything you need, distro block, fuse up front, etc. for like $50.
Hell, I've got 1/0 gauge running through my Pathfinder, and I've got one 600w amp for the entire install. Better too large than too small.

[TechSys]

So you have a 8gauge and 4gauge wire running from the battery to your amps? Or am I just reading that wrong?

[geolemon]

So you have a 8gauge and 4gauge wire running from the battery to your amps? Or am I just reading that wrong?

You are reading that wrong - but this is a good opportunity to clarify what really matters, so that you can have a good solid understanding to do your own system.

I have two vehicles...
Let's walk through the Civic, it's the smaller system (at least wiring-wise).

I originally only had a 400w amp, for my sub... and then later added a small 50x2 (or something like that, it's been a long time ) amp for my components.
So, my total current draw was just small enough that I could get away with 4 gauge comfortably.

First thing I added (as with everyone ) was my main power wire... you can buy these as a "wiring kit" these days, incuding your underhood fusing, distribution block, RCA cables, turn-on wire, etc. for cheap.

I used 4 gauge wire...
From the battery (I'd suggest a replacement battery terminal, but you can often get away with a ring terminal on the end of the 4 gauge), less than 16" down the wire from the battery, you want your main fuse installed.

(It should be at least as large as the sum of all the fusing for everything in your trunk. This fuse doesnt' protect that equipment, it protects the wire (and really the car) from fire, should something happen to the wire, causing a short. You don't want this fuse popping under daily operation, obviously. ]

From the main fuse, the long, long 4 gauge wire travels back to the trunk.
(run it through an empty grommet, or an oversized grommet with room next to it, in the firewall - 95% of the time at least, there is one you can poke through, no drilling through the firewall required. If you do drill, use a grommet in the hole, or that sharp metal will potentially cut the power wire, quickly teaching you a lesson on why that main fuse exists! )
It usually is connected to a terminal block.

Now is a good time to point out again that it isn't just wire GAUGE that matters - length factors in as well. Ultimately, what you care about is "how much resistance is in this length of wire".
You can lower the resistance of a wire by making it shorter, and you can lower the resistance of a wire by making it larger in diameter.

I point this out because the "main power wire" is very long (between the battery and the distribution block in the trunk).
And generally the short links of power wire from the distribution block and the amps are very short.
...which means that not only can you "get away with" using 8 gauge wire for the short power wire between the amp and the distribution block - but actually that short wire might ultimately have less resistance than the long run of 4 gauge!

I have two runs of 8 gauge wire going from my distribution block to my amp - each of them less than 4 feet long.

I also upgraded the power wires underhood - and again, because these were so short, I used 8 gauge for all of them.
I replaced the factory battery ground - and made sure the contact was bare metal-on-metal (paint is an insulator!).
I replaced the factory engine ground (think of this as your alternator's ground).
I replaced the positive power link from the battery to the alternator. Even being a longer than the other two of the "magic 3", this wire was less than 4 feet long.

Now - if I had bigger amps, say... an 800w amp and a 100x2 amp or something... upgrading to a larger wire - maybe 2 gauge would be wise. 8 gauge on the short links might still be OK...

2 gauge is hard to find though, and 1/0 is common and has become cheap.
I generally skip right to this option. :happy055:
and if you were running something larger... over 1000w... I'd go right to this anyway.

Again, factor in length...
1/0 on the main power wire. Maybe 4 gauge to an amp that draws a ton of power (ie. big sub amp). 8 gauge is probably fine for a stereo amp.
The engine and battery ground underhood, if they are less than a foot - probably 8 gauge is fine, for the main power wire I might step up to 4 gauge, because it's longer and we're talking about drawing more current.
Or, you could go 4 gauge for everything that's not the main wire - no harm in that either.

Hopefully that's helpful and not confusing.
It's always safer to run a larger wire than you need, when in doubt.
That's the bottom line.