Projects Better fusible link replacement ?

I want to replace my old fusible links with a safer more modern system. I have 2, 12ga fusible links ( both are going to diferent 8ga wire curcuits)..... I also have a 16ga fusible link ( going to 12ga wire circuits)
What would be a good relacement for those fusible links ? Since fusible links are a slow acting/slow blow safety system....I will want something of that type . Also what amperage of replacement sytle fuses should I be using ???

 

Circuit breakers ...

 

OK, but if you had a short or other problem, won't circuit breakers just cool down and they try to power up the systen over and over again. I would think you would want one of the modern slow blow tpye fuses. Im just unsure of the best choice and more importinly what amperage I would need.

 

I’m not sure on modern, but I burned one up (my fault) went to NAPA and said I need one of these.
If memory serves, they were color coded, or maybe had a number on them.

 

Marine circuit breakers need to be manually reset

I use these

 

Most circuit breakers are manual reset, the auto-reset type are usually embedded in electric motor windings or they are on the headlight switch of some older cars. Radio Shack, RS etc would sell the manual reset type.

 

Think about what the purpose the fusible link serves?
It seems it is similar to a fuse (or a circuit breaker). It protects the wire if there is a current overload, or a short.
I don't think cars being produced today use a fusible link, so your vintage ride should be able to be retrofitted to eliminate/substitute for the fusible links.
Replacement fuses or circuit breakers need to be sized to protect the wires. 8 gauge wire will need a good sized fuse. We need to figure out what size? What is that wire powering? Or is it the wire from the alternator?
Let's see what @Crazy Steve can add here.

 

On both of my cars I use the maxi fuse blade style fuse holders and fuses. For main power I use an 80 amp and smaller sized to whatever the load is. The nice thing about these fuses and fuse holders is the fuses can be purchased at any auto parts store, and holders are waterproof with a rubber boot that closes over the fuse.
These look just like the fuses used in all new cars, except much larger to handle the amperage. Never had a 80a. main fuse blow yet, but I keep one spare in each car just in case.

 

That's true of a type I circuit breaker. If you use a type II circuit breaker, it will remain open until you power down the circuit. Type II circuit breakers were common in heavy truck applications.

 

How is going from one usable , serviceable system ( fusible links) to another (fuses /breakers) an " upgrade , seems more of a sideways move ?

 

"Lateral"

 

Yes the 8ga wire / 12ga fusible link is for the alternator ( a 78amp mopar alternator)....The 12ga wires/16ga fusible link goes to other non fused items (lights, fuse box power etc)

 

I have already communicated with him in a PM, he apparently didn't like my answer... And he isn't giving the reason for why, which is germane to this.

It's my opinion that doing this is a waste of time and money.

 

Let me ask you this. Are you still using fusible links in your cars/ or builds ? if yes OK. If No why not ? Also if No what are you using. I'm rewiring the engine bay, and thought it would be a good time to protect the wire with something less prone to cause a possible fire.

 

"#8 AWG copper is rated at 50 amps. I know the wire will safely carry more, but that is just a general guideline. I would start with a 50 amp Maxi fuse as close as possible to the battery [or alternator?] and see what happens."
This seems to be the advice I found in multiple sites.

 

This thread is similar to your question. You might find some useful info, especially post #6.
https://www.jalopyjournal.com/forum/threads/main-fuse-size-and-wire-gauge.1237338/

 

Im having a problem understanding why one disconnect mechanism is less safe than the other ?

 

Maxi fuse for sure. I have one 50 Amp that came with the harness kit.

 

Myself as well. I don’t know what they (fl’s) are made of, but recall them being somewhat encapsulated in a sheathing? of some sort. They are sized smaller that the wire they protect. Must be due to the the properties of what they are actually made from, as opposed to putting in a 14 gauge wire to protect a 10 gauge wire.
Seems the 14 g fusable link carries the same current at the 10 wire does, performs fine, until an issue arises, then opens up.
Ya, trading one over current protection device for another, seems like fixing a problem that isn’t there.

 

My self not a engineer, I use both
On main power supply ,I use a Circuit
Breaker to power Fused junction / fuse box, ( like shown in post 5 )
If circuit would trip , Check for issue
Between batt power to fuse
box /junction.
If fuse blown / burnt ,
Issue between fuse to Application ?

 

I guess I’m weird, I don’t have anything on the charge wire, just like how the manufacturers do it….

 

It's the aftermarket creating a need for a product that's not really needed , without doing this , many companies would quickly go out of business . Consider if computer companies quit inventing operating systems that won't function on your existing device , the same for phone/ personal devices . My grandparents used the same black bakelite rotary phone for decades ( that the phone company provided ), try doing that with a portable device today . In order to be one of the Kool kids , you are pressured into buying , buying ,buying .

 

I talked to Mr. American Autowire at Louisville one year about fusing the line out of the alternator.
Conclusion, probably not really needed, even though they regularly recommend it.

 

I think the choice of size for a maxi-fuze has to also consider the maximum output of the alternator on the vehicle.

 

Yes, that depends on the insulation used, and also if it's free air, or bundled in a tight group. But generally it can take much more for short times.

 

Factory didn't fuse the alternator charge wire, and almost all used a wire size much smaller than would be considered correct for amperage they put out. Not sure on new cars as i don't mess with wiring on anything new. Don't think I've ever seen one burnt up, or running hot to the touch, even when an alternator itself burnt up from internal short.

 

" Internal shorts" wouldn't effect the output wire seeing as the output wire is external ..LOL

 

Not quite correct.
The wire gauge should be chosen to accommodate the alternator output, safely.
If you feel a fuse is necessary, the fuse size should be chosen to protect the wire from overload or short.

 

And therein lies the problem...

Almost no one sizes the alternator output wire to match maximum output. But output is usually much lower, so no problem. As has been pointed out, it can take the overcurrent for short periods.

Overcurrent protection is supposed to be sized to the wire, but in this case has to be able to withstand the maximum current that may occur to avoid nuisance tripping.

If the overcurrent device rating is substantially higher than the wire ampacity (25% or more), the first thing that's gone is your overload protection. If it's even higher, you may not have even short circuit protection. Think about it... Once you get up to 80 amps or more, that's arc-welding current. You can burn holes in sheetmetal at those levels. And unless you get a 'solid' short, what's more likely is the wire will rub against the steel and erode the steel and/or start melting individual wire strands in half until either the wire parts or the remaining strands get hot from overload and start a fire.

You can install those fuses if it makes you feel better, but it's probably not going to work how you think it will when you need it...

 

The equivalent of 15A outlets on 14ga wire with 30 amp fuses