# Big three upgrade. Fuse block completley melted down. So what the heck happened!?



## Script (Apr 6, 2010)

You can see my original install here:

My Build log. Zapco, Rainbow, BM-MKIII - F150online Forums

And here is my power wire fuse as it was today after leaving me stranded...



















I was running a 120A mini ANL fuse in waterproof fuse holder. Stock Alternator... The wire terminals at the fuse are toast so i will need to rebuild the whole new power wire. 

I don't know where to go from here.. I wasn't even using my system when this happened... Did my alternator malfunction? Was it fused too low, and if so why didn't the fuse just blow? Why the melt down? Very confused....


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## t3sn4f2 (Jan 3, 2007)

Wait, that was your alternator wire?! Oh ok then go off my original post that I edited thinking it was your system positive that melted while listening to music. IE poor termination at the fuse block. Again check all termination points regardless.


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## Script (Apr 6, 2010)

Yes it is the Alternator power wire. You deleted your first post though.

I am thinking maybe i had it under fused...


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## t3sn4f2 (Jan 3, 2007)

Script said:


> Yes it is the Alternator power wire. You deleted your first post though.
> 
> I am thinking maybe i had it under fused...


Dunno the details on your alt, but for that fuse size and only the car running of the alt. during the day, I'd say it's impossible your under fused.

It melted because poor contact at the fuse block somewhere caused that spot to heat up till it failed.


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## Script (Apr 6, 2010)

t3sn4f2 said:


> Dunno the details on your alt, but for that fuse size and only the car running of the alt. during the day, I'd say it's impossible your under fused.
> 
> It melted because poor contact at the fuse block somewhere caused that spot to heat up till it failed.


So you think maybe the bolts weren't tight enough that actually held the wires to the fuse? Or perhaps they became lose over time and caused arcing from the wire to the fuse?


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## t3sn4f2 (Jan 3, 2007)

Script said:


> So you think maybe the bolts weren't tight enough that actually held the wires to the fuse? Or perhaps they listened over time and caused arcing from the wire to the fuse?


Can't tell from those pics, but when something fails like that it fails at the point where there was the faulty contact.

That being said, how can the wire weld to the "fuse"? Or did you mean fuse block input terminal? If so, then the reason is still hard to tell. Just check everything everywhere to make sure that it is properly terminated.


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## Richv72 (May 11, 2012)

Your fuse probably was bad, the whole purpose of the fuse is to be a weak link in case something like this happens. i have no idea how someone could test the actual fuse prior to installing it though. What brand of fuse was it?. either that or the fuse holder was not rated to carry 120 amps.


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## t3sn4f2 (Jan 3, 2007)

Whatever it is, it's at the output side at least.


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## Richv72 (May 11, 2012)

What brand of fuse holder was this so I can avoid it?.


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## robert_wrath (Apr 24, 2011)

Whatever the issue is now, you need to replace the wire burnt out along with the InLine Fuse Block.


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## t3sn4f2 (Jan 3, 2007)

cajunner said:


> *could be your battery is toast, and the alternator was constantly dumping current into it causing the fuse holder to heat up from resistance.*If it's a cheap fuse holder it's going to have spring clips that are riveted to the metal body on either side of the fuse terminals.
> 
> These are notorious for heating up because the springy metal is tempered, and not a great conductor of amps. Dissimilar metals, rivets, cheap pot metal with a chrome cover, and lipstick on a pig come to mind.
> 
> check the battery first, then buy a good fuse holder.


A 125 amp fuse properly implemented into a wiring scheme, melting a fuse block, when a stock alternators that wishes it could put out that type of constant current on a good day? Not even mentioning the non audio load.


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## RNBRAD (Oct 30, 2012)

Combination of things. Constant current through a less than perfect connection thats already hot from sitting on the radiator hose. Cheap plastic, probably less than ideal metals and platings for conduction and walla. Buy a Streetwires FHXL4 and mount it closer to your battery away from heat.


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## t3sn4f2 (Jan 3, 2007)

Looks like the stock cable already has some type of fusible link. I'd put it back and that's that.

As always, yet another reason not to mess with a stock alternator cable when using a stock alternator.


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## Script (Apr 6, 2010)

I did the mod so long ago that i was really having trouble remembering what brand the fuse holder was until i realized that i was running an identical fuse holder in-line with my stereo system power wire.
It’s a KnuKonceptz In-Line Waterproof Mini-ANL Fuse Holder with a 120A fuse from the same site.

Knukonceptz product detail for IN-LINE WATERPROOF MINI-ANL FUSE HOLDER

From what I can find out online, the alternator is either rated at 110amps or 130amps… 

Here are some more pictures…

This is the identical fuse holder running to the system.



















Here are some more angles of the melted fuse holder.




























By examining the photos I believe that the heat was generated where the fuse bolted to the block on the battery side of the fuse holder. As you can see the other side of the fuse holder is still intact, you can even see part of the fuse there.

I don't believe I have the OEM power wire any longer. Since doing this mod over two years ago i have moved twice and it probably got tossed at some point...


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## Justin Zazzi (May 28, 2012)

The fuse must have been intact during the failure because the heat needed to cause that much damage must have been from too much current passing through too small an area. The only way current could flow through that area would be to/from the alternator and battery, so the fuse must have been intact initially.

I had a similar failure on my alternator positive lead because the wire connected at the alternator disintegrated over time, forcing the current to pass through an ever-smaller cross section. Eventually the remaining wire touching the terminal on the alternator was so small that the current passing through it generated enough heat to melt the terminal and weld the locknut to it, severing the connection entirely. There was never an over-current situation from the point of view of the fuse, because the fuse is sized to protect the 8 gauge wire and the amount of current passing through the wire never changed, only the cross sectional area of the wire. This allowed the heat build-up and failure.

You may have had something similar. The contact point between the fuse and the screw-down terminal on the battery side may have become weak or loose, causing the normal amount of current to pass through a smaller cross-sectional area. The fuse and box were already at higher temperatures than normal from sitting on top of the radiator hose (near 100 degrees C) so only a little extra heat was needed for a catastrophic failure.

At least, this is what I can come up with from seeing pictures and trying to help over the internet. In the future, try to keep all your power cables far away from the radiator hoses and exhaust manifolds. I'm pretty sure the factory wiring was not attached the way you routed it, so try to copy what was originally there if you need ideas for routing.

-J


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## Script (Apr 6, 2010)

I think i found the OEM power wire from the dealership for under 30 bucks, I still need to talk to the service center in case im wrong about the part number that i found online.

If the OEM wire ends up being cost prohibitive, and i make another wire, can i use some high temp thread lock, or a star washer to keep things in place?

Thanks for all of the help!


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## starboy869 (Dec 16, 2006)

There's your problem. Knu. They have this 'melting' problem before. I remember seeing a few threads on 'melted fused blocks' back in 2006-2008 time era and each one of them was Knu.

What happened is a connection got loose, created huge amount of resistance (heat), etc., This time around spend a couple dollars more and get stinger block, and some lockite blue.

btw aren't you glad you went down the big three bandwagon tour with your stock alt?


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## Script (Apr 6, 2010)

Haha! Oh don't you know it!! I had a 2 hour walk in the snow today with nothing to think about but how glad I am to have hopped on the big three bandwagon..


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## Richv72 (May 11, 2012)

Wow man that looks even worse when its not covered up. I would email the knuconceptz company and show them how their POS fuse holder almost burned down your car. Well at least no one got hurt and your car isnt destroyed.


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## knukonceptz (Mar 6, 2008)

Thank for whoever emailed me this link. To answer the question about what happened, its a loose connection. Heat is generated by resistance, resistance is caused by a loose contact. Over time the output side, of what appears to be the fuse itself came loose. Heating and cooling in the engine bay can cause expansion/contraction of metals potentially loosening a connection. The holder was mounted to what appears to be a radiator hose, which will add vibration to the issue. According to the OP, this install was completed over 2 year ago. 

The model fuse holder is used in several of our amp kits and we produce over 5000 of this item each year. If our product caused failure, we want to know about it. Given the data on this model I have on hand, we have had less then 5 failures reported in 2012.


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## sebberry (May 1, 2008)

I still can't figure out why fuse blocks are using small set screws on fine stranded, large gauge wire. They make contact with what, 50% of the wire strands at most?

Crimp lugs onto the damn wires and bolt them to the fuse block. If the OEMs are using crimped lugs/bolted terminals at the battery, alternator and starter then there's probably a good reason for it.


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## Script (Apr 6, 2010)

Ideally I would like to solder the fuse directly to the wire and have a case around it just to keep everything straight and protected exactly like the OEM wire... Keep it simple. 

Instead I took a wire with two terminal connections (points of failure as in my case) and turned it into a wire wire six terminal connections (six points of failure)... 

Unfortunately I cant really find a kit to facilitate such a thing...


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## co_leonard (Aug 14, 2009)

That happened to me before with a generic mini-ANL fuse holder.

Turns out I didn't tighten one of the allen bolts enough - not the one holding the fuse, the one holding the thick wire. 

All that current flowing through a loose connection heated it up and eventually melted it. 

I know because although the allen bolt had melted down, I could still jiggle the gauge-4 wire inside the terminal. 

In the end, it was my mistake. Should have used a ferrule.


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## Script (Apr 6, 2010)

I am not really trying to call the Knu fuse block a crap product or anything. It was designed to be one of the cheapest out there, and its my own fault for using on such a vital part of the vehicle. That kind of heat would obviously melt any fuse holder, and Knu definitely is not alone in leaving lock washers out of the mix. Though had lock washers been included, I could have at least logically made the connection to the risk, perhaps i should have anyway... I think is a little odd that i have not seen a single ANL fuse holder with lock washers.. Yet, when I look up Mega fuse holders I cant seem to find any WITHOUT lock washers!! Maybe car audio should take a few hints from other industries... Cars vibrate, that's why you see lock-tight and lock washers so widely implemented on them.. Make sense right?

I think i am more concerned about what could have happened than what actually did happen.. Perhaps i should shift to positive thinking, at least i didn't get stranded out in the middle of the mountains, and at least my truck didn't go down in a blaze of glory.


Anyway, long term reliability is essential to me. Now more than ever. So I have basically decided to purchase this fuse holder and run a Mega fuse...

Littelfuse 298900 Automotive Single Terminal Fuse Holder : Amazon.com : Automotive

It's simple, I can run wire terminals directly to the screws that hold the fuse, it comes with lock washers, and it is made out of the type of high temperature plastic that is actually used in engine-bays from the factory.. So unless someone can give me a pretty darn good reason otherwise, I'm threw with car audio fuse holders... They have never looked OEM enough for my taste anyway....


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## co_leonard (Aug 14, 2009)

Very nice fuse holder! 

I especially like that the wire terminal can bolt directly to the fuse.


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## Richv72 (May 11, 2012)

Ill give knukonceptz credit, they came on here and addressed this issue very quickly. Now are they going to give you a free replacement?


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## Script (Apr 6, 2010)

I agree. And I really wasn't trying to turn this into a Knu bashing thread. As I look for replacement fuse holders, this type of failure appears to be a real possibility for many different brands.

I blame myself more than anyone... For the install location, not using thread-lock, and you know, cheeping out on the one component of my system that effects the reliability of my vehicle the most...

With that said, I would respectfully reject a free replacement if offered. I am developing other plans.


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## req (Aug 4, 2007)

good on knu to get here.

bravo. some locktite next time would help solve the problem of a loosening-over-time fuse block


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## SaturnSL1 (Jun 27, 2011)

Richv72 said:


> Ill give knukonceptz credit, they came on here and addressed this issue very quickly. Now are they going to give you a free replacement?


Not trying to start an argument but why should Knu give him a free replacement?


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## t3sn4f2 (Jan 3, 2007)

*Re: Big three upgrade. Fuse block completely melted down. So what the heck happened!?*

I'd be VERY careful (ie don't)to use any type of thread lock on a screw of which is part of the conduction path . Even worse if it were to spill out of the shallow screw hole and onto the base of the block. Then you would have compromised conduction on the screw path and on the main surface. The goes another fuse block.

I'd simply install it correctly the first time. 

-screw it down to a solid fixed surface
-use a proper gauge wire for the terminal
-use the correct size tool to tighten down the bolts so that you can torque it without stripping it.


And just as important as securing the block to a solid surface is securing the wires at two near points on each side of the block. That way the wire can't vibrate up and down, flex the input blocks that are mounted on a plastic housing, and vibrate the fuse screw loose. Looks like that is what happened here with the un-attached bat to fuse cable.



Script said:


>


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## Script (Apr 6, 2010)

That's all fine and dandy. But after looking at other manufacturers for heavy duty fuse holders beyond the car audio world, ALL of them seem to use some sort of locking mechanism, typically a lock washer.

Or in this case, nylon lock nuts.










Evan after installing it in a secure place, its ridiculous not to have something on the bolt to keep it down. Something that everyone outside the car audio scene seems to have already realized...


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## t3sn4f2 (Jan 3, 2007)

Script said:


> That's all fine and dandy. But after looking at other manufacturers for heavy duty fuse holders beyond the car audio world, ALL of them seem to use some sort of locking mechanism, typically a lock washer.
> 
> Or in this case, nylon lock nuts.
> 
> ...


Haven't you heard, car audio is more about pretty than functional. The consumer prefers a pretty, seamless block that gives the impression of better current flow.


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## RNBRAD (Oct 30, 2012)

t3sn4f2 said:


> Haven't you heard, car audio is more about pretty than functional. The consumer prefers a pretty, seamless block that gives the impression of better current flow.


Pretty and functional


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## t3sn4f2 (Jan 3, 2007)

RNBRAD said:


> Pretty and functional


For $7? 

http://www.knukonceptz.com/productDetail.cfm?prodID=FH-44


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## RNBRAD (Oct 30, 2012)

t3sn4f2 said:


> For $7?
> 
> Knukonceptz product detail for IN-LINE WATERPROOF MINI-ANL FUSE HOLDER


 Got me there.


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## sebberry (May 1, 2008)

There's also Blue Sea Systems:

ANL Fuse Blocks - PN - Blue Sea Systems

They even list torque spec so you know how much to tighten the nut. 

I'll be using the Safety Hub (SafetyHub 150 Fuse Block*—*Blue Sea Systems) for my install. I just can't find anything with the same level of quality and features in the car audio world.


And this is why I'll be crimping lugs on my cables:

The set screw on a fuse block (not Knu) barely made contact with half the wires on this 4GA cable:


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## SaturnSL1 (Jun 27, 2011)

Not every stand of wire needs to be in contact with the screw in the distro. That wire looks perfectly fine, no sign of overheating or anything.


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## sebberry (May 1, 2008)

That's because it never went in the car  I put it in and removed it just to see the contact area.


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## t3sn4f2 (Jan 3, 2007)

SaturnSL1 said:


> Not every stand of wire needs to be in contact with the screw in the distro. That wire looks perfectly fine, no sign of overheating or anything.


If you put a 4 gauge wire in a 0 gauge pot, it will look like that. Is that ok?, no way. The only part that is being squeezed onto the Walls it the little area under the set screw. That is until likely vibration and improper mounting wiggle those strands loose.

The idea is to pack the well with as many stands as can fit while having the set screw out completely. Then when you screw it down there is no room for the wire to _move out of the way_ into empty non conducting space. And since there aren't really any standards that these blocks or wires need to follow, you can't rely on 0 wire for 0 block. 

If the wire you get is smaller than optimum, you should strip away extra insulation and fold over how ever many strand bundles needed to fill that well completely. Then cut of the extra straight ends. Also straighten out the twist in the wire so that is doesn't happen latter when you tighten the screw. Reducing the overall area and leaving a loose connection.

I used to have a high quality Monster dual fuse block that had a 3 way input pot. One from each side and a center at the end. The problem was that it was a through and through pot for all inputs. So if you used the center input it would squeeze the wire out into the adjacent wells. Leaving only the set screw and bottom part as the contact area. No side walls fro the wire to even lightly touch. Looked like the one in the following link.

http://img.auctiva.com/imgdata/1/4/3/4/4/0/9/webimg/596080431_tp.jpg


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## Script (Apr 6, 2010)

I think the idea with those set screws is that wires that are not in contact with the screw get pushed outward and make connection with the side of the block.

I agree with you though, I don't think it's that great of a design. Especially when you consider dependability 10 or even 20yrs down the road.

Regardless if you really want all wires to contact i think the best solution is a terminal crimped and soldered to the wire. Which is what I will be doing.


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## 07azhhr (Dec 28, 2011)

sebberry said:


> And this is why I'll be crimping lugs on my cables:
> 
> The set screw on a fuse block (not Knu) barely made contact with half the wires on this 4GA cable:


Keep in mind that the set screw pushes the rest of the strands down and out to make contact with the rest of the inside of the terminal. 



Script said:


> That's all fine and dandy. But after looking at other manufacturers for heavy duty fuse holders beyond the car audio world, ALL of them seem to use some sort of locking mechanism, typically a lock washer.
> 
> Or in this case, nylon lock nuts.
> 
> ...


 
Notice that they also include spots to screw it down to a solid surface.


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## t3sn4f2 (Jan 3, 2007)

07azhhr said:


> Keep in mind that the set screw pushes the rest of the strands down and out to make contact with the rest of the inside of the terminal.


Doesn't look like those strands were pushed (ie pressed) onto anything.


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## 07azhhr (Dec 28, 2011)

t3sn4f2 said:


> Doesn't look like those strands were pushed (ie pressed) onto anything.


Just saying in general. If someone is using a smaller gauge then the terminal is made for then there is not going to be much contact but that is human error now isn't it. Just like you pointed out above. Use the right size terminal for the wire you are using and vice-versa and it will push out. If you look at that pic you can see a lot of jacket on that cable which suggests a low strand count for the given gauge. That again is not the terminals fault but is with the manu and the end user.


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## sebberry (May 1, 2008)

Keep in mind that was a Scosche efx wiring kit - the wire and the fuse block were from the same kit. 

That wasn't the wrong wire for the fuse block.


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## pentavolvo (Nov 12, 2008)

Between me and some buddys 4 of those same KNU fuse holders have failed, never on big3 always on the power feed.


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## Mr. Nice Guy (Jul 21, 2011)

Haven't read the whole thread, but if I were a betting man, I'd say that your fuse was not designed to blow soon enough. Certain fuses will actually handle up to 50% more than their ratings for a decent amount of time before blowing. If you had 200 amps surging through a wire that could only handle 120A (whether due to size, quality, or possible damage), and your fuse didn't blow, then your fuse is likely at fault. You basically need to make sure that your fuse will blow at am amperage that is less than your wire's rated amperage capacity. That's still only half of the equation though. If your wire was rated to handle, say, 250A, and the max amperage draw of the loads at the end of that line are more like 200A, then you likely had a short condition which overloaded the wire with current and caused it to melt. If that's the case, then you should make us aware of the maker and rating of the fuse you used, because they should never be used again if they allowed such a catastrophic result from a short. You could have 200A wire and a way overrated 300A fuse, but that fuse should have blown before your wire melted.

Buy better, lower rated fuses, and start over.


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## t3sn4f2 (Jan 3, 2007)

Mr. Nice Guy said:


> Haven't read the whole thread, but if I were a betting man, I'd say that your fuse was not designed to blow soon enough. Certain fuses will actually handle up to 50% more than their ratings for a decent amount of time before blowing. If you had 200 amps surging through a wire that could only handle 120A (whether due to size, quality, or possible damage), and your fuse didn't blow, then your fuse is likely at fault. You basically need to make sure that your fuse will blow at am amperage that is less than your wire's rated amperage capacity. That's still only half of the equation though. If your wire was rated to handle, say, 250A, and the max amperage draw of the loads at the end of that line are more like 200A, then you likely had a short condition which overloaded the wire with current and caused it to melt. If that's the case, then you should make us aware of the maker and rating of the fuse you used, because they should never be used again if they allowed such a catastrophic result from a short. You could have 200A wire and a way overrated 300A fuse, but that fuse should have blown before your wire melted.
> 
> Buy better, lower rated fuses, and start over.


gotta read the thread.


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## Richv72 (May 11, 2012)

SaturnSL1 said:


> Not trying to start an argument but why should Knu give him a free replacement?


I would think any company would want to replace that piece because it has their name on it. The right thing to do would be for them to say "send it in and we will look at it and replace it with one that wont loosen up". I have never ever used loc tite on anything that has to do with my wiring.


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## Justin Zazzi (May 28, 2012)

Be sure to attach it somewhere other than the radiator hose this time around


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## Script (Apr 6, 2010)

Interesting read from BCAE:

FUSES




> MEGA®/AMG Bolt-on Fuses:
> These fuses are not really popular in car audio but are widely available and may be an option for high current protection in the main power line (from the battery). They are available in sizes ranging from 100-250 amps. As you can see, there is no big fancy block of metal with set screws here. This type of fuse requires ring terminals. In commercial/industrial applications, this is a better option because there are fewer points of connection. You'll never see the bling type fuse holders where safety and reliability are of the utmost importance.


I found this exact fuse holder in stock at NAPA today for 10 bucks. It's heavy duty plastic with a rubber cover and has 1/4" bolts with locking star washers. Looks like a good peace, going in the truck tomorrow. And NOT on the radiator hose!


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## BigAl205 (May 20, 2009)

RNBRAD said:


> Cheap plastic, probably less than ideal metals and platings for conduction and *walla*.


*walla*:
_interjection_ \wä-ˈlä\
orig. Retarded English

*Definition of walla*
—a term used by idiots who don't know how to spell _VOILÀ

_ex._ "I sat down on the toilet, closed my eyes, and WALLA...I made poopies"
_


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## SeniorXJ (Feb 10, 2012)

This thread came up in a search & so i wanted to add my story to this cause this happened to me with the exception that the failure point caused a fire that took down my beloved jeep!! 

I had done the big 3 on my old jeep & altho i cant remember the fuse holder brand, i do remember it felt a bit cheapy in hand & had a volt meter that never worked. This was also the alternator wire & fuse block that decided one cold day after not being driven for over a day to just up & statrt an engine fire that left my jeep totaled. 

A hard lesson learned so dont be cheap in areas like this cause id hate for this to happen to anyone!!


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## Script (Apr 6, 2010)

Wow that sucks that you lost your whole vehicle because of it. I figured I would come back and post my solution, just in case it could help someone out in the future. 

Mega fuse holder with star washers and double nuts, the top nuts are nylon locking. The ring terminals are both crimped and soldered. Maybe its a little overkill 

I don't care what anyone says, ill never be convinced that audio fuse holders don't suck. The irony being that this safer set-up was far cheaper than the high-end audio fuse holders, albeit slightly more work to set-up ...


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## t3sn4f2 (Jan 3, 2007)

Script said:


> Wow that sucks that you lost your whole vehicle because of it. I figured I would come back and post my solution, just in case it could help someone out in the future.
> 
> *Mega fuse holder with star washers and double nuts, the top nuts are nylon locking. The ring terminals are both crimped and soldered. Maybe its a little overkill *
> 
> I don't care what anyone says, ill never be convinced that audio fuse holders don't suck. The irony being that this safer set-up was far cheaper than the high-end audio fuse holders, albeit slightly more work to set-up ...


Nice job. You solution is excellent just as long as you tightened the nuts correctly. In that application you'd want to tighten the first star washer nut fully, then hold it in place with an open end wrench and then tighten the nylon nut till its tight. If not, they will be fixed but not apply the initial pressure intended.


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## Richv72 (May 11, 2012)

I made my own using micarta for a base so it will be heat resistant.


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