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Can a slow blow fuse be used in place of a fusible link? I have always wondered why the factory uses fusible links - I assume they are cheaper.But harder to check & replace.
In my main power supply (NOT starter cable) from the battery to the horn relay, I was planning to use a fuse - 30 or 40 amp.
Pros / cons ?

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283V8;

The fusible link is just a piece of wire. It was cheap, quick, and simple, but inaccurate in the protection it provided.

I would think a fuse could be used. I know Honda used to do it (and maybe still does). I really don't know if a 40A fuse would be big enough though. A good alternator could put out up to 70 amps which could blow a 40A fuse. You could also consider something like a 60A circuit breaker. The Honda's had a 40A fast blow fuse, but their alternators were fairly small and probably quite current limited.

Peter
 

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F o r d s have used big fuses in some cars. Replaced a 100 (?) amp in an Escort a while back. Didn't think the engine would produce 100 amp current.
 

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A fusable link would be less prone to blowing during a surge or voltage spike in the electrical circuit.

If connected with a crimped and soldered connection, a fusable link wouldn't have the potential problem of corrosion an the connections where a fuse would be plugged in.

If you really feel the need for a "fuse" in the main line, think about using a resetable circuit breaker. Go to a boat supply and see what is available with screw lugs to hook up the wires.

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Wes. Vann
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Here's my take on the whole thing,

The fusible link is a very important item in the vehicle, if it goes bad, it can literally leave you stranded in the middle of nowhere. After all, it feeds, all of the interior lights, equipment and starter solenoid.

The factory needed something that would provide protection for the long run of wire feeding all of this. It had to be reliable and cheap. Voila! the fusible link.

In my opinion there would be nothing wrong with an actual fuse IF you calculate the total current drawn--NEVER NEVER EVER PUT A BIGGER (HIGHER RATED) FUSE THAN WHAT SHOULD BE !. i.e. If the maximum the wiring harness is meant to handle oh let's say 30 amps, use a 30 amps or less, not 40 or 50 or you'll have a nice electrical fire
possibility.

Here's the catch; if you use a fuse you need a fuse holder, and it BETTER BE A GOOD ONE!

Corrosion, heat and vibration will take their toll on that fuse holder and if it is a cheapo to begin with, well let's just say I hope you don't mind being stranded when it breaks.

Hope that helps.


Joe
 

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How many amps your alternator "puts out" is irrelevant. Having a 100 amp alternator simply means that you can draw up to 100 amps without burning the alternator. You need at least an 8 ga. primary wire to feed everything if your system is drawing that much current. If you don't have several power amps for a boom-boom sound system, you probably don't draw nearly that much current.

Here's a link with a chart of wire sizes with ampacities relative to length. http://www.sherco-auto.com/wirespec.htm
That should help you get a good idea of what you're looking at.

Make sure that your fuse will blow before your wire burns. That way if your feeder wire gets cut and goes directly to ground, you won't have to deal with a fire.

It is common practice for people to use a short piece of 14 ga. wire as a fusible link between the battery and the 10 ga. feeder wire.

Chad Landry
Baton Rouge, LA
 

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Hey guys, I thought I understood fusible links until Chad's last comment about using a piece of wire as a fusible link.

Is a "fusible link" a thing, i.e., something you can actually buy? Or is it simply the concept of using a smaller wire to act as a fuse? Another post recently mentioned buying fusible link wire at an auto parts store. Could someone describe the difference between a 14 ga wire and a 14 ga fusible link, or is it all smoke and mirrors? Thanks, TK

[This message has been edited by TK-70 (edited 02-17-2000).]
 

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You can actually buy a fusible link at the parts store. But physically it's nothing more than a lighter gauge piece of wire that will burn long before your 10 ga. does.

Following is the definition of a fusible link as taken from Tex Smith's "How To Do Electrical Systems" by Skip Readio.

"A fusible link is a length of wire that is 4 wire gauges smaller than the wire it is protecting that is placed in an electrical circuit in such a manner as to provide electrical overload protection. In the event of an overload, the fusible link will melt and interrupt the flow of current in the circuit."

For my application I plan to solder a short piece of 14 ga into the wire and use heat shrink tubing to cover the solder joints. I just think it looks more professional than the fusible links that they sell in the stores.
 

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Geez;

Why do people go on about never putting too large a fuse in the circuit and then say that a fusible link is just a piece of smaller gauge wire?

Does anyone think a fusible link provides anything close to the predictable protection that a fuse would???

You can size a fuse up to the point where the wire gets so hot it will begin to light things on fire. This will be much larger than just the maximum continous current of the fuse.

During a short, the wire will probably see 500+ amps before something gives. This won't do any damage to the wire because it is very short term.

The fusible link has possible corrossion failure points at each end of it's connection so it isn't fail safe that way either.

I personally would look for a 60 to 80A circuit breaker to replace the fusible link.

Peter
 

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During the install of my Painless Kit, there no mention of using a Fusible Link in the manual. Instead, their system uses a 50A fuse on the main feed. It looks like an overgrown ATO fuse.

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Don't forget that if you use a normal piece of wire in place of a fusible link,the insulation will melt before the wire burns thru leaving it open to a direct short. When a fusible link burns out, the insulation stays intact.
 
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