why fuse within 18 inches of battery?
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=108159
Printed Date: May 13, 2025 at 1:11 PM
Topic: why fuse within 18 inches of battery?
Posted By: thumpinbass
Subject: why fuse within 18 inches of battery?
Date Posted: October 14, 2008 at 11:12 PM
You keep hearing that you should have an inline fuse 18" from your battery. Why 18"? Why not 12" or 24"? OK, so now the reason why I ask. I have a kicker inline fuse that I can use at my battery. It is not weatherproof to put in my engine, so I was going to run my power wire through the firewall (which I would need to do anyways) and put the inline fused just inside the cab of my truck. Then run it back to my amps. It will be very close to being 18" to where I put the inline fuse at, but could be up to 24". Is this a problem? Is there a reason why everyone says 18". I'm just curious, plus want to know if 24" will be ok. Thanks for your help! Allen
Replies:
Posted By: audiocableguy
Date Posted: October 14, 2008 at 11:53 PM
The Inline fuse is there to protect the wire. Period. The closer to the battery, the better protected that wire will be. The fuse should be installed before going through the firewall even if it is less than 18".
Use a rubber or hard plastic grommet if you can't use a factory one.
IASCA specs 18" Max, the Marine Safety Reg. says 12" Max. Closer the better.
Posted By: megaman
Date Posted: October 15, 2008 at 8:44 AM
I hear this a lot from my customers doing thier own installs. As stated above, the fuse protects the wire. If you put the fuse after the firewall, then there's the chance that if the wire were to be chaffed by the hole in the firewall that it runs through, then it could short to ground and burn up. If you put the fuse as close to the battery as possible, then the fuse will do it's job if the wire were to become damaged and short to ground. Frankly there's no real reason to put the inline fuse inside the cab at all.
Posted By: thumpinbass
Date Posted: October 15, 2008 at 9:33 AM
I knew why the fuse is there. I have done numerous installs before, nothing competition though. I was just curious why it's always recommended to be 18". That's all. And the reason why I asked about doing it inside (the inline fuse) is because I happen to have an inline fuse already, but not made for the engine compartment, so why spend all the money on another one if there was a chance I could use the one I currently have. I had just checked and the inline fuse would have been right around 12" - 18" from the battery if I had decided to do it inside the cab since my battery is right against the firewall in my AV. I will be using the stinger grommet for 0g for my firewall. All my wiring is stinger products and all my car audio is Kicker. Allen
Posted By: DYohn
Date Posted: October 15, 2008 at 9:57 AM
thumpinbass wrote:
so why spend all the money on another one if there was a chance I could use the one I currently have.
Because it is always better to do it correctly than to just "make it work." That's the difference between an installer and just some guy who knows how to wire car stereo.  ------------- Support the12volt.com
Posted By: KPierson
Date Posted: October 15, 2008 at 12:39 PM
I've always heard "within 18"" of the battery. You can go less, it's just not a good idea to go more. If the fuse is within 18" of the battery there isn't much room for the wire to short out. A few years back a few companies had fuse holders that mounted right to the battery - that is technically the best way to go as that way the entire wire is protected. However, that isn't aslways feasable due to space restrictions. ------------- Kevin Pierson
Posted By: audiocableguy
Date Posted: October 15, 2008 at 3:01 PM
Buss/Blue Sea Systems offers these terminal fuses that have a bracket that mounts directly to the battery post, very clean and somewhat cost effective.
https://bluesea.com/category/5/22/productline/overview/379
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