Electrically, what causes a fuse to melt?
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Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=85841
Printed Date: April 30, 2024 at 8:25 AM
Topic: Electrically, what causes a fuse to melt?
Posted By: coppellstereo
Subject: Electrically, what causes a fuse to melt?
Date Posted: November 18, 2006 at 9:44 PM
Electrically - what causes a fuse to melt instead of break.
I've heard it is loose connections, which to me, would be adding resistance to the circuit ... correct?
I assume the circuit is just dissipating extra heat, but not extra current ... is this right?
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Replies:
Posted By: haemphyst
Date Posted: November 18, 2006 at 10:37 PM
The element in a fuse is just a wire... same as the 4 gauge wire it is protecting. It is a smaller gauge of wire, sure, but of a known melting point and resistance. This is why the elements in fuses are all different size, and the smaller the wire, the higher the temperature for a given amount of current running through it.
A 100A fuse, for example might offer a resistance of .033 ohms, but at 100A running through it, that is a dissipation of 3.3 watts. 3.3 watts with no heatsink, in a glass tube, with no air convection, and it will eventually get hot enough to melt...
That's pretty much it, really...
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: coppellstereo
Date Posted: November 19, 2006 at 12:05 AM
I gotcha.
I've seen whole fuseholders melt, could something this simple cause it? Customers always ask me why, and I cant come up with the best reason. They always just assume they should up their fuse size.
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Posted By: coppellstereo
Date Posted: November 19, 2006 at 12:33 AM
If the circuit's resistance doubles, it can only carry half the power, right? so is the other half of the power dissipated as heat?
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Posted By: aznboi3644
Date Posted: November 19, 2006 at 12:33 AM
um...they melt because most these days are made of crappy plastic that melts...If you get a man's fuse holder like this the holder wouldn't even break a sweat lol
https://www.bluesea.com/product.asp?Product_Id=23471&d_Id=&l1=&l2=
Posted By: coppellstereo
Date Posted: November 19, 2006 at 12:46 AM
ive never seen an ANL fuse holder melt, ive only seen the agu and maxi fuses/holders melt.
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Posted By: aznboi3644
Date Posted: November 19, 2006 at 1:18 AM
I've need my friends fuse holder melt...woulda burned to hell but he noticed smoke coming from his hood...burned a ridge in his air filter box too lol
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