I know its standard fare to wire the fuse in your power line close to the battery....but I never knew why. I've seen people with their fuse mounted to their amp rack, and the fuse holders I have both have screwholes (and I don't think you'd screw-mount it anywhere under the hood). From my little bit of stereo knowledge I'd think it'd be safe anywhere in the power loop. Could someone explain to me why I'm wrong?

 

The fuse is designed to blow before the insulation on the wire melts and the wire arcs to ground. When you pull more current than the wire can deliver, the wire heats up, and will eventually melt or catch on fire. Or it could catch something nearby on fire.

If you mount it next to the battery, a short anywhere beyond that will blow the fuse. If you mount it in the trunk, a short may occur before the fuse where there is no protection. In the trunk shoud be a fuse box for the various amps and processors. The fuse at the battery is for the power wire. Don't ever think it is for the devices powered by the wire in the trunk.

 

It all comes down to that ole saying the "the shorter the distance the better the response".

 

Thats more of what I was thinking. I have trouble understanding the difference in consequences with a short occurring before the fuse if the fuse was in the trunk, vs. a short occurring and the fuse by the battery catching it - does it just mean a fraction of a second more time that the battery is being drained/effected, since the short has to travel the distance of the wire all the way to the trunk?

I ask because I mounted a fuse in the trunk, and it blew after about a week on a large draw. The wire under the hood and everything seems fine. What damage could I have done?

Thanks for putting up with my ignorance.

 

Only damage is the 50 cent fuse you will have to replace

 

Actually, there is a problem here. The difference is that you had your short, or whatever in the trunk. If that same short had been under the hood, in the passenger compartment or anywhere between the battery and the fuse, it would not hav blown. The fuse in general blows when twice it's rated current tries to pass, for some allotted amound of time. I can't remember how long it is. So say you have 4 gauge cable running to your trunk. You fuse it with an 80 amp fuse. So it's entirely possible that you will be pulling 100, 120 or so amps all day long. But when it creaps up to 160 amps, the fuse will blow. That's a lot of current. Enough to do serious damage. Now imagine we have the same 4 gauge wire attached to the battery, no fuse. In the trunk is a fuse just before the amp. One day you decide to drive some friends to a party. They pile in the back seat. Now these are young people and they move around alot. Especially with the latest mp3 cranking with your new system. Unfortunately your 4 gauge cable runs right under "Big Joey's" ****. Everyone thinks Joey let loose but it's really your power wire. After the party you go out to the car and get in. What's that smell you think. Then the engine won't start. The battery is dead becauese you have a huge cable shorted to ground and no one can give you a jump start. Now you have to call Mom and Pop and give them directions to your favorite rave hang-out.

We won't mention what your seat looks like if there is anything left to see.

 

I was always told that the close fuse was for protection in a crash. Say you get t-boned and the power wire gets cut. It can arc to the body and start a fire. But, if the fuse is right next to the battery, it will blow first...

 

jmax is correct on the short issue but is used for a little more than that.it really is very important and if the value of the system is worth a 10$ setup, it is definately worth it
It is in a sence like a "surge protector"...it blows for shorts in wire and also for surges in your electrical system..say, battery starter or altenator.If you were to get into an accident, or for some odd reason your altenator decides to go out and send a 300a surge to the battery, same scenario for starter...It is more of a limitation device really, the d-block fuse will blow as well for a short..
as for positioning, really doesn't matter, closer the better...IASCA rules was it had to be no more than 18" off the battery and if it was further or not there no show..that's why show cars are close to the battery..
Althought in a sence it is "insurance" and not really necessary, why send a surge to your amps, crossovers, eq's if there then to speakers and risk blowing them at the cost of a 2.00 fuse and a 10.00$ fuse holder be it inline? now, for the more elaborate who step up to ANL fuses or circuit breakers at a cost maybe as high as 40$ but if it saves my 1k in amps 800 in processors and 2k in speakers, it's worth it isn't it?

 

Thanks for everyone for putting things a little more into perspective. I already mounted a fuse in the trunk, so I guess as not to disturb my amp placement/power wire length run, I'll leave it there and add another fuse up by the battery where one belongs. Do you guys actually mount your fuseholders up in the engine bay, and if so, how/where? In my Acura, the shop that did the install left it floating, and that's how I've seen it in a friends ride as well.


jmax - hehe, that scenario might have happened four years ago or so to me. None of my relatively small number of friends ever want to ride in the Max because of my no-smoking ban, no more raves/parties even really, and I'd probably be calling the AAA guy out to blockbuster, best buy, or the local beer run places. But just the thought of 4ga burning through into the seats and other places...*shudder*...

 

The bonus fuse is a waste of time.

 

several options really blizz......you can screw it to the firewall, fender or get a tie down strap for your battery and mount it to it.just remember though if in metal, it is best if you take a "self tapper" screw and screw the screw in...take it out, take another screw and put a little silicone on it when you screw it back in.this will prevent rust and also keep the paint from chipping further from vibration

 

Here is a picture of my fuse setup. Two 4-guages with 60-amp fuses.

Tony

 

My fuse I guess you could say is free-floating. If anything attached to 1/0 could be described as free-floating. It's real easy to attach the wire before or after the fuse or both, with wire ties.