fuse

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=106917
Printed Date: April 29, 2024 at 8:11 AM

Topic: fuse

Posted By: still_walkin
Subject: fuse
Date Posted: August 20, 2008 at 6:22 PM

I have a setup that consist of a total amperage of 175a and my main fuse is 250 0 guage and fou4 to my amps. I plan to upgrade my system and didn't want to rerun a 4 guage before then run a 0 later on when I decided to do this upgrade so currently I have a 0 guage with a 250a fuse and a 175 amperage system is this safe till I do my upgrade or I need to lower the fuse amperage or am I ok

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1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"

Replies:

Posted By: KPierson
Date Posted: August 20, 2008 at 7:05 PM

I personally would fuse it at 175A. Download a data sheet for a 250A fuse and read up on how long it takes for a 250A fuse to blow - then compare it to the time a 175A fuse takes to blow. The difference in time would be how much longer your electrical system (stereo, ECU, BCM, PCM, TC, etc) is needlessly exposed to an over current situation if something were to happen.

Fuses are safety devices, over sizing them doesn't make much sense from a safety standpoint. However, at the same time as long as your fuse is small enough to protect the wire you won't have to worry about the wire itself overheating and catching on fire.

So, I guess to summarize - the wire is safe, but your electrical system could potentially be subjected to more abuse then it needs to be subjected to before the oversized fuse blows.

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Kevin Pierson

Posted By: KPierson
Date Posted: August 20, 2008 at 7:15 PM

OK, I just looked up the data sheet (https://www.uniprod.com.pl/upload/File/littelfuse/298.pdf)

For a 250A at 1,000A (assumed current from direct short to ground) the fuse will blow in 0.9 seconds. Thats an eternity to sensitive electronics.

For a 175A at 1,000A the fuse will blow in 0.3 seconds

So, in case of catostrophic failure you will be subjecting your entire electrical system to pretty much the worst case scenario for 3x longer then you need to be.

If your available current is lower then 1,000A (which it very well could be, especially if your alternator has short circuit protection and quits providing power). A 250A fuse can carry 550A across it for 10 whole seconds. The 175A will only do about 350A for 10 seconds before blowing.

As you can see, the closer you get to your instantanious current capacity the longer it will take to blow the fuse.

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Kevin Pierson

Posted By: audiocableguy
Date Posted: August 20, 2008 at 7:15 PM

Fuse every time you change wire size! If you have a 250A on the 1/0 AWG
and you have 4 AWG attached to that 1/0 AWG without fuses, the max fuse size would be 100A. Remember the main fuse at the battery is to protect the wire! You must main fuse to the smallest wire size connected. I fuse 4 AWG at 100 Amps, this is just me.

Now if you are splitting from 1/0 AWG to 4 AWG with a fused distro block 250 Amp at the battery and 100 to 150 amp fuse to each 4 AWG.

Unless you are planning a "monster" upgrade you can run most amps off 1/0 AWG and 4 AWG. Your A-6000 will need it's own 1/0 AWG!

Posted By: still_walkin
Date Posted: August 20, 2008 at 7:15 PM

Thanks for the reply.If my memory serves me right 175 is a 4 guage fuse right

I Currently have a ho alternator 240amps from highoutputalternator.com

From the battery(0)250a and to alt 250a
To the non fused distro 3 amps (1) a2200hct and (2) a2002t amps.

-------------
1993 sdv
Alpine 4x6 6x9 5 1/4 swr-10d4
alpine v60
12.5 VGA flip down
Nettop pc w/10" touch screen
78nova
5-re audio 5x7 ,10" sub &
Xtx-500.5
"Take the faceplate off get the jumperpack"